Injection molded screening apparatuses and methods

ABSTRACT

Screening members, screening assemblies, methods for fabricating screening members and assemblies and methods for screening materials are provided for vibratory screening machines that incorporate the use of injection molded materials. Use of injection molded screen elements provide, inter alia, for: varying screening surface configurations; fast and relatively simple screen assembly fabrication; and a combination of outstanding screen assembly mechanical and electrical properties, including toughness, wear and chemical resistance. Embodiments of the present invention use a thermoplastic injection molded material.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 15/201,865, filed Jul. 5, 2016, which is a continuation of Ser. No.14/268,101, filed May 2, 2014, now U.S. Pat. No. 9,409,209, which is acontinuation-in-part of U.S. patent application Ser. No. 13/800,826,filed Mar. 13, 2013, which claims the benefit of U.S. Provisional PatentApplication Ser. Nos. 61/652,039 filed May 25, 2012, and 61/714,882filed Oct. 17, 2012, the entire contents of each of which isincorporated herein by reference.

FIELD

The present disclosure relates generally to material screening. Moreparticularly, the present disclosure relates to screening members,screening assemblies, methods for fabricating screening members andassemblies and methods for screening materials.

BACKGROUND

Material screening includes the use of vibratory screening machines.Vibratory screening machines provide the capability to excite aninstalled screen such that materials placed upon the screen may beseparated to a desired level. Oversized materials are separated fromundersized materials. Over time, screens wear and require replacement.As such, screens are designed to be replaceable.

Replacement screen assemblies must be securely fastened to a vibratoryscreening machine and are subjected to large vibratory forces.Replacement screens may be attached to a vibratory screening machine bytensioning members, compression members or clamping members.

Replacement screen assemblies are typically made of metal or a thermosetpolymer. The material and configuration of the replacement screens arespecific to a screening application. For example, due to their relativedurability and capacity for fine screening, metal screens are frequentlyused for wet applications in the oil and gas industry. Traditionalthermoset polymer type screens (e.g., molded polyurethane screens),however, are not as durable and would likely not withstand the roughconditions of such wet applications and are frequently utilized in dryapplications, such as applications in the mining industry.

Fabricating thermoset polymer type screens is relatively complicated,time consuming and prone to errors. Typical thermoset type polymerscreens that are used with vibratory screening machines are fabricatedby combining separate liquids (e.g., polyester, polyether and acurative) that chemically react and then allowing the mixture to cureover a period of time in a mold. When fabricating screens with fineopenings, e.g., approximately 43 microns to approximately 100 microns,this process can be extremely difficult and time consuming. Indeed, tocreate fine openings in a screen, the channels in the molds that theliquid travels through have to be very small (e.g., on the order of 43microns) and all too often the liquid does not reach all the cavities inthe mold. As a result, complicated procedures are often implemented thatrequire close attention to pressures and temperatures. Since arelatively large single screen (e.g., two feet by three feet or larger)is made in a mold, one flaw (e.g., a hole, i.e., a place where theliquid did not reach) will ruin the entire screen. Thermoset polymerscreens are typically fabricated by molding an entire screen assemblystructure as one large screening piece and the screen assembly may haveopenings ranging from approximately 43 microns to approximately 4000microns in size. The screening surface of conventional thermoset polymerscreens normally have a uniform flat configuration.

Thermoset polymer screens are relatively flexible and are often securedto a vibratory screening machine using tensioning members that pull theside edges of the thermoset polymer screen away from each other andsecure a bottom surface of the thermoset polymer screen against asurface of a vibratory screening machine. To prevent deformation whenbeing tensioned, thermoset polymer assemblies may be molded with aramidfibers that run in the tensioning direction (see, e.g., U.S. Pat. No.4,819,809). If a compression force were applied to the side edges of thetypical thermoset polymer screens it would buckle or crimp, therebyrendering the screening surface relatively ineffective.

In contrast to thermoset polymer screens, metal screens are rigid andmay be compressed or tensioned onto a vibratory screening machine. Metalscreen assemblies are often fabricated from multiple metal components.The manufacture of metal screen assemblies typically includes:fabricating a screening material, often three layers of a woven wiremesh; fabricating an apertured metal backing plate; and bonding thescreening material to apertured metal backing plate. The layers of wirecloth may be finely woven with openings in the range of approximately 30microns to approximately 4000 microns. The entire screening surface ofconventional metal assemblies is normally a relatively uniform flatconfiguration or a relatively uniform corrugated configuration.

Critical to screening performance of screen assemblies (thermosetpolymer assemblies and metal type assemblies) for vibratory screeningmachines are the size of the openings in the screening surface,structural stability and durability of the screening surface, structuralstability of the entire unit, chemical properties of the components ofthe unit and ability of the unit to perform in various temperatures andenvironments. Drawbacks to conventional metal assemblies include lack ofstructural stability and durability of the screening surface formed bythe woven wire mesh layers, blinding (plugging of screening openings byparticles) of the screening surface, weight of the overall structure,time and cost associated with the fabrication or purchase of each of thecomponent members, and assembly time and costs. Because wire cloth isoften outsourced by screen manufacturers, and is frequently purchasedfrom weavers or wholesalers, quality control can be extremely difficultand there are frequently problems with wire cloth. Flawed wire cloth mayresult in screen performance problems and constant monitoring andtesting is required.

One of the biggest problems with conventional metal assemblies isblinding. A new metal screen may initially have a relatively large openscreening area but over time, as the screen is exposed to particles,screening openings plug (i.e., blind) and the open screening area, andeffectiveness of the screen itself, is reduced relatively quickly. Forexample, a 140 mesh screen assembly (having three layers of screencloth) may have an initial open screening area of 20-24%. As the screenis used, however, the open screening area may be reduced by 50% or more.

Conventional metal screen assemblies also lose large amounts of openscreening area because of their construction, which includes adhesives,backing plates, plastic sheets bonding layers of wire cloth together,etc.

Another major problem with conventional metal assemblies is screen life.Conventional metal assemblies don't typically fail because they get worndown but instead fail due to fatigue. That is, the wires of the wovenwire cloth often actually break due to the up and down motion they aresubject to during vibratory loading.

Drawbacks to conventional thermoset polymer screens also include lack ofstructural stability and durability. Additional drawbacks includeinability to withstand compression type loading and inability towithstand high temperatures (e.g., typically a thermoset polymer typescreen will begin to fail or experience performance problems attemperatures above 130° F., especially screens with fine openings, e.g.,approximately 43 microns to approximately 100 microns). Further, asdiscussed above, fabrication is complicated, time consuming and prone toerrors. Also, the molds used to fabricate thermoset polymer screens areexpensive and any flaw or the slightest damage thereto will ruin theentire mold and require replacement, which may result in costly downtimein the manufacturing process.

Another drawback to both conventional metal and thermoset polymerscreens is the limitation of screen surface configurations that areavailable. Existing screening surfaces are fabricated with relativelyuniform opening sizes throughout and a relatively uniform surfaceconfiguration throughout, whether the screening surface is flat orundulating.

The conventional polymer type screens referenced in U.S. ProvisionalApplication No. 61/652,039 (also referred to therein as traditionalpolymer screens, existing polymer screens, typical polymer screens orsimply polymer screens) refer to the conventional thermoset polymerscreens described in U.S. Provisional Patent Application Ser. No.61/714,882 and the conventional thermoset polymer screens describedherein (also referred to herein and in U.S. Provisional PatentApplication Ser. No. 61/714,882 as traditional thermoset polymerscreens, existing thermoset polymer screens, typical thermoset polymerscreens or simply thermoset screens). Accordingly, the conventionalpolymer type screens referenced in U.S. Provisional Application No.61/652,039 are the same conventional thermoset polymer screens referenceherein, and in U.S. Provisional Patent Application Ser. No. 61/714,882,and may be fabricated with extremely small screening openings (asdescribed herein and in U.S. Provisional Patent Application Ser. No.61/714,882) but have all the drawbacks (as described herein and in U.S.Provisional Patent Application Ser. No. 61/714,882) regardingconventional thermoset polymer screens, including lack of structuralstability and durability, inability to withstand compression typeloading, inability to withstand high temperatures and complicated, timeconsuming, error prone fabrication methods.

There is a need for versatile and improved screening members, screeningassemblies, methods for fabricating screening members and assemblies andmethods for screening materials for vibratory screening machines thatincorporate the use of injection molded materials (e.g., thermoplastics)having improved mechanical and chemical properties.

SUMMARY

The present disclosure is an improvement over existing screen assembliesand methods for screening and fabricating screen assemblies and partsthereof. The present invention provides extremely versatile and improvedscreening members, screening assemblies, methods for fabricatingscreening members and assemblies and methods for screening materials forvibratory screening machines that incorporate the use of injectionmolded materials having improved properties, including mechanical andchemical properties. In certain embodiments of the present invention athermoplastic is used as the injection molded material. The presentinvention is not limited to thermoplastic injection molded materials andin embodiments of the present invention other materials may be used thathave similar mechanical and/or chemical properties. In embodiments ofthe present invention, multiple injection molded screen elements aresecurely attached to subgrid structures. The subgrids are fastenedtogether to form the screen assembly structure, which has a screeningsurface including multiple screen elements. Use of injection moldedscreen elements with the various embodiments described herein provide,inter alia, for: varying screening surface configurations; fast andrelatively simple screen assembly fabrication; and a combination ofoutstanding screen assembly mechanical, chemical and electricalproperties, including toughness, wear and chemical resistance.

Embodiments of the present invention include screen assemblies that areconfigured to have relatively large open screening areas while havingstructurally stable small screening openings for fine vibratoryscreening applications. In embodiments of the present invention, thescreening openings are very small (e.g., as small as approximately 43microns) and the screen elements are large enough (e.g., one inch by oneinch, one inch by two inches, two inches by three inches, etc.) to makeit practical to assemble a complete screen assembly screening surface(e.g., two feet by three feet, three feet by four feet, etc.).Fabricating small screening openings for fine screening applicationsrequires injection molding very small structural members that actuallyform the screening openings. These structural members are injectionmolded to be formed integrally with the screen element structure.Importantly, the structural members are small enough (e.g., in certainapplications they may be on the order of approximately 43 microns inscreening surface width) to provide an effective overall open screeningarea and form part of the entire screen element structure that is largeenough (e.g., two inches by three inches) to make it practical toassemble a relatively large complete screening surface (e.g., two feetby three feet) therefrom.

In one embodiment of the present invention a thermoplastic material isinjection molded to form screening elements. Previously thermoplasticshave not been used with the fabrication of vibratory screens with finesize openings (e.g., approximately 43 microns to approximately 1000microns) because it would be extremely difficult, if not impossible, tothermoplastic injection mold a single relatively large vibratoryscreening structure having fine openings and obtain the open screeningarea necessary for competitive performance in vibratory screeningapplications.

According to an embodiment of the present disclosure, a screen assemblyis provided that: is structurally stable and can be subjected to variousloading conditions, including compression, tensioning and clamping; canwithstand large vibrational forces; includes multiple injection moldedscreen elements that, due to their relatively small size, can befabricated with extremely small opening sizes (having dimensions assmall as approximately 43 microns); eliminates the need for wirecloth;is lightweight; is recyclable; is simple and easy to assemble; can befabricated in multiple different configurations, including havingvarious screen opening sizes throughout the screen and having variousscreening surface configurations, e.g., various combinations of flat andundulating sections; and can be fabricated with application-specificmaterials and nanomaterials. Still further, each screen assembly may becustomized to a specific application and can be simply and easilyfabricated with various opening sizes and configurations depending onthe specifications provided by an end user. Embodiments of the presentdisclosure may be applied to various applications, including wet and dryapplications and may be applied across various industries. The presentinvention is not limited to the oil and gas industry and the miningindustry, it may be utilized in any industry that requires separation ofmaterials using vibratory screenings machines, including pulp and paper,chemical, pharmaceuticals and others.

In an example embodiment of the present invention, a screen assembly isprovided that substantially improves screening of materials using athermoplastic injection molded screen element. Multiple thermoplasticpolymer injection molded screen elements are securely attached tosubgrid structures. The subgrids are fastened together to form thescreen assembly structure, which has a screening surface includingmultiple screen elements. Each screen element and each subgrid may havedifferent shapes and configurations. Thermoplastic injection moldingindividual screen elements allows for precise fabrication of screeningopenings, which may have dimensions as small as approximately 43microns. The grid framework may be substantially rigid and may providedurability against damage or deformation under the substantial vibratoryload burdens it is subjected to when secured to a vibratory screeningmachine. Moreover, the subgrids, when assembled to form the completescreen assembly, are strong enough not only to withstand the vibratoryloading, but also the forces required to secure the screen assembly tothe vibratory screening machine, including large compression loads,tension loads and/or clamping loads. Still further, the openings in thesubgrids structurally support the screen elements and transfervibrations from the vibratory screening machine to the elements formingthe screening openings thereby optimizing screening performance. Thescreen elements, subgrids and/or any other component of the screenassembly may include nanomaterials and/or glass fibers that, in additionto other benefits, provide durability and strength.

According to an example embodiment of the present disclosure, a screenassembly is provided having a screen element including a screen elementscreening surface with a series of screening openings and a subgridincluding multiple elongated structural members forming a grid frameworkhaving grid openings. The screen element spans at least one of the gridopenings and is attached to a top surface of the subgrid. Multipleindependent subgrids are secured together to form the screen assemblyand the screen assembly has a continuous screen assembly screeningsurface having multiple screen element screening surfaces. The screenelement includes substantially parallel end portions and substantiallyparallel side edge portions substantially perpendicular to the endportions. The screen element further includes a first screen elementsupport member and a second screen element support member orthogonal tothe first screen element support member. The first screen elementsupport member extends between the end portions and is approximatelyparallel to the side edge portions. The second screen element supportmember extends between the side edge portions and is approximatelyparallel to the end portions. The screen element includes a first seriesreinforcement members substantially parallel to the side edge portionsand a second series of reinforcement members substantially parallel tothe end portions. The screen element screening surface includes screensurface elements forming the screening openings. The end portions, sideedge portions, first and second support members and first and secondseries of reinforcement members structurally stabilize screen surfaceelements and screening openings. The screen element is formed as asingle thermoplastic injection molded piece.

The screening openings may be rectangular, square, circular, and oval orany other shape. The screen surface elements may run parallel to the endportions and form the screening openings. The screen surface elementsmay also run perpendicular to the end portions and form the screenopenings. Different combinations of rectangular, square, circular andoval screening openings (or other shapes) may be incorporated togetherand depending on the shape utilized may run parallel and/orperpendicular to the end portions.

The screen surface elements may run parallel to the end portions and maybe elongated members forming the screening openings. The screeningopenings may be elongated slots having a distance of approximately 43microns to approximately 4000 microns between inner surfaces of adjacentscreen surface elements. In certain embodiments, the screen openings mayhave a distance of approximately 70 microns to approximately 180 micronsbetween inner surfaces of adjacent screen surface elements. In otherembodiments, the screening openings may have a distance of approximately43 microns to approximately 106 microns between inner surfaces ofadjacent screen surface elements. In embodiments of the presentinvention, the screening openings may have a width and a length, thewidth may be about 0.043 mm to about 4 mm and the length may be about0.086 mm to about 43 mm. In certain embodiments, the width to lengthratio may be approximately 1:2 to approximately 1:1000.

Multiple subgrids of varying sizes may be combined to form a screenassembly support structure for screen elements. Alternatively, a singlesubgrid may be thermoplastic injection molded, or otherwise constructed,to form the entire screen assembly support structure for multipleindividual screen elements.

In embodiments that use multiple subgrids, a first subgrid may include afirst base member having a first fastener that mates with a secondfastener of a second base member of a second subgrid, the first andsecond fasteners securing the first and second subgrids together. Thefirst fastener may be a clip and the second fastener may be a clipaperture, wherein the clip snaps into the clip aperture and securelyattaches the first and second subgrids together.

The first and second screen element support members and the screenelement end portions may include a screen element attachment arrangementconfigured to mate with a subgrid attachment arrangement. The subgridattachment arrangement may include elongated attachment members and thescreen element attachment arrangement may include attachment aperturesthat mate with the elongated attachment members securely attaching thescreen element to the subgrid. A portion of the elongated attachmentmembers may be configured to extend through the screen elementattachment apertures and slightly above the screen element screeningsurface. The attachment apertures may include a tapered bore or maysimply include an aperture without any tapering. The portion of theelongated attachment members above the screening element screeningsurface may be melted and may fill the tapered bore, fastening thescreen element to the subgrid. Alternatively, the portion of theelongated attachment members that extends through and above the aperturein screening element screening surface may be melted such that it formsa bead on the screening element screening surface and fastens the screenelement to the subgrid.

The elongated structural members may include substantially parallelsubgrid end members and substantially parallel subgrid side memberssubstantially perpendicular to the subgrid end members. The elongatedstructural members may further include a first subgrid support memberand a second subgrid support member orthogonal to the first subgridsupport member. The first subgrid support member may extend between thesubgrid end members and may be approximately parallel to the subgridside members. The second subgrid support member may extend between thesubgrid side members and may be approximately parallel to the subgridend members, and substantially perpendicular to the subgrid edgemembers.

The grid framework may include a first and a second grid frameworkforming a first and a second grid opening. The screen elements mayinclude a first and a second screen element. The subgrid may have aridge portion and a base portion. The first and second grid frameworksmay include first and second angular surfaces that peak at the ridgeportion and extend downwardly from the peak portion to the base portion.The first and second screen elements may span the first and secondangular surfaces, respectively.

According to an example embodiment of the present invention, a screenassembly is provided having a screen element including a screen elementscreening surface with a series of screening openings and a subgridincluding multiple elongated structural members forming a grid frameworkhaving grid openings. The screen element spans at least one grid openingand is secured to a top surface of the subgrid. Multiple subgrids aresecured together to form the screen assembly and the screen assembly hasa continuous screen assembly screening surface comprised of multiplescreen element screening surfaces. The screen element is a singlethermoplastic injection molded piece.

The screen element may include substantially parallel end portions andsubstantially parallel side edge portions substantially perpendicular tothe end portions. The screen element may further include a first screenelement support member and a second screen element support memberorthogonal to the first screen element support member. The first screenelement support member may extend between the end portions and may beapproximately parallel to the side edge portions. The second screenelement support member may extend between the side edge portions and maybe approximately parallel to the end portions. The screen element mayinclude a first series reinforcement members substantially parallel tothe side edge portions and a second series of reinforcement memberssubstantially parallel to the end portions. The screen element mayinclude elongated screen surface elements running parallel to the endportions and forming the screening openings. The end portions, side edgeportions, first and second support members, first and second series ofreinforcement members may structurally stabilize the screen surfaceelements and the screening openings.

The first and second series of reinforcement members may have athickness less than a thickness of the end portions, side edge portionsand the first and second screen element support members. The endportions and the side edge portions and the first and second screenelement support members may form four rectangular areas. The firstseries of reinforcement members and the second series of reinforcementmembers may form multiple rectangular support grids within each of thefour rectangular areas. The screening openings may have a width ofapproximately 43 microns to approximately 4000 microns between innersurfaces of each of the screen surface elements. In certain embodiments,the screening openings may have a width of approximately 70 microns toapproximately 180 microns between inner surfaces of each of the screensurface elements. In other embodiments, the screening openings may havea width of approximately 43 microns to approximately 106 microns betweeninner surfaces of each of the screen surface elements. In embodiments ofthe present invention, the screening openings may have a width of about0.043 mm to about 4 mm and length of about 0.086 mm to about 43 mm. Incertain embodiments, the width to length ratio may be approximately 1:2to approximately 1:1000.

The screen elements may be flexible.

The subgrid end members, the subgrid side members and the first andsecond subgrid support members may form eight rectangular grid openings.A first screen element may span four of the grid openings and a secondscreen element may span the other four openings.

A central portion of the screening element screening surface mayslightly flex when subject to a load. The subgrid may be substantiallyrigid. The subgrid may also be a single thermoplastic injection moldedpiece. At least one of the subgrid end members and the subgrid sidemembers may include fasteners configured to mate with fasteners of othersubgrids, which fasteners may be clips and clip apertures that snap intoplace and securely attach the subgrids together.

The subgrid may include: substantially parallel triangular end pieces,triangular middle pieces substantially parallel to the triangular endpieces, a first and second mid support substantially perpendicular tothe triangular end pieces and extending between the triangular endpieces, a first and second base support substantially perpendicular tothe triangular end pieces and extending the between the triangular endpieces and a central ridge substantially perpendicular to the triangularend pieces and extending the between the triangular end pieces. A firstedge of the triangular end pieces, the triangular middle pieces, and thefirst mid support, the first base support and the central ridge may forma first top surface of the subgrid having a first series of gridopenings. A second edge of the triangular end pieces, the triangularmiddle pieces, and the second mid support, the second base support andthe central ridge may form a second top surface of the subgrid having asecond series of grid openings. The first top surface may slope downfrom the central ridge to the first base support and the second topsurface may slope down from the central ridge to the second basesupport. A first and a second screen element may span the first seriesand second series of grid openings, respectively. The first edges of thetriangular end pieces, the triangular middle pieces, the first midsupport, the first base support and the central ridge may include afirst subgrid attachment arrangement configured to securely mate with afirst screen element attachment arrangement of the first screen element.The second edges of the triangular end pieces, the triangular middlepieces, the second mid support, the second base support and the centralridge may include a second subgrid attachment arrangement configured tosecurely mate with a second screen element attachment arrangement of thesecond screen element. The first and second subgrid attachmentarrangements may include elongated attachment members and the first andsecond screen element attachment arrangements may include attachmentapertures that mate with the elongated attachment members therebysecurely attaching the first and second screen elements to the first andsecond subgrids, respectively. A portion of the elongated attachmentmembers may extend through the screen element attachment apertures andslightly above a first and second screen element screening surface.

The first and second screen elements each may include substantiallyparallel end portions and substantially parallel side edge portionssubstantially perpendicular to the end portions. The first and secondscreen elements may each include a first screen element support memberand a second screen element support member orthogonal to the firstscreen element support member, the first screen element support memberextending between the end portions and being approximately parallel tothe side edge portions, the second screen element support memberextending between the side edge portions and may be approximatelyparallel to the end portions. The first and second screen elements mayeach include a first series reinforcement members substantially parallelto the to the side edge portions and a second series of reinforcementmembers substantially parallel to the end portions. The first and secondscreen elements may each include elongated screen surface elementsrunning parallel to the end portions and forming the screening openings.The end portions, side edge portions, first and second support members,first and second series of reinforcement members may structurallystabilize screen surface elements and screening openings.

One of the first and second base supports may include fasteners thatsecure the multiple subgrids together, which fasteners may be clips andclip apertures that snap into place and securely attach subgridstogether.

The screen assembly may include a first, a second, a third and a fourthscreen element. The first series of grid openings may be eight openingsformed by the first edge of the triangular end pieces, the triangularmiddle pieces, and the first mid support, the first base support and thecentral ridge. The second series of grid openings may be eight openingsformed by the second edge of the triangular end pieces, the triangularmiddle pieces, the second mid support, the second base support and thecentral ridge. The first screen element may span four of the gridopenings of the first series of grid openings and the second screenelement may span the other four openings of the first series of gridopenings. The third screen element may span four of the grid openings ofthe second series of grid openings and the fourth screen element mayspan the other four openings of the second series of grid openings. Acentral portion of the first, second, third and fourth screening elementscreening surfaces may slightly flex when subject to a load. The subgridmay be substantially rigid and may be a single thermoplastic injectionmolded piece.

According to an example embodiment of the present disclosure, a screenassembly is providing having a screen element including a screen elementscreening surface with screening openings and a subgrid including a gridframework with grid openings. The screen element spans the grid openingsand is attached to a surface of the subgrid. Multiple subgrids aresecured together to form the screen assembly and the screen assembly hasa continuous screen assembly screening surface that includes multiplescreen element screening surfaces. The screen element is a thermoplasticinjection molded piece.

The screen assembly may also include a first thermoplastic injectionmolded screen element and a second thermoplastic injection molded screenelement and the grid framework may include a first and second gridframework forming a first grid opening and a second grid opening. Thesubgrid may include a ridge portion and a base portion, the first andsecond grid frameworks including first and second angular surfaces thatpeak at the ridge portion and extend downwardly from the peak portion tothe base portion. The first and second screen elements may span thefirst and second angular surfaces, respectively. The first and secondangular surfaces may include a subgrid attachment arrangement configuredto securely mate with a screen element attachment arrangement. Thesubgrid attachment arrangement may include elongated attachment membersand the screen element attachment arrangement may include apertures thatmate with the elongated attachment members thereby securely attachingthe screen elements to the subgrid.

The subgrid may be substantially rigid and may be a single thermoplasticinjection molded piece. A section of the base portion may include afirst and a second fastener that secure the subgrid to a third and afourth fastener of another subgrid. The first and third fasteners may beclips and the second and fourth fasteners may be clip apertures. Theclips may snap into clip apertures and securely attach the subgrid andthen another subgrid together.

The subgrids may form a concave structure and the continuous screenassembly screening surface may be concave. The subgrids may form a flatstructure and the continuous screen assembly screening surface may beflat. The subgrids may form a convex structure and the continuous screenassembly screening surface may be convex.

The screen assembly may be configured to form a predetermined concaveshape when subjected to a compression force by a compression assembly ofa vibratory screening machine against at least one side member of thevibratory screen assembly when placed in the vibratory screeningmachine. The predetermined concave shape may be determined in accordancewith a shape of a surface of the vibratory screening machine. The screenassembly may have a mating surface mating the screen assembly to asurface of the vibratory screening machine, which mating surface may berubber, metal (e.g., steel, aluminum, etc.), a composite material, aplastic material or any other suitable material. The screen assembly mayinclude a mating surface configured to interface with a mating surfaceof a vibratory screening machine such that the screen assembly is guidedinto a fixed position on the vibratory screening machine. The matingsurface may be formed in a portion of at least one subgrid. The screenassembly mating surface may be a notch formed in a corner of the screenassembly or a notch formed approximately in the middle of a side edge ofthe screen assembly. The screen assembly may have an arched surfaceconfigured to mate with a concave surface of the vibratory screeningmachine. The screen assembly may have a substantially rigid structurethat does not substantially deflect when secured to the vibratoryscreening machine. The screen assembly may include a screen assemblymating surface configured such that it forms a predetermined concaveshape when subjected to a compression force by a member of a vibratoryscreening machine. The screen assembly mating surface may be shaped suchthat it interfaces with a mating surface of the vibratory screeningmachine such that the screen assembly may be guided into a predeterminedlocation on the vibratory screening machine. The screen assembly mayinclude a load bar attached to an edge surface of the subgrid of thescreen assembly, the load bar may be configured to distribute a loadacross a surface of the screen assembly. The screen assembly may beconfigured to form a predetermined concave shape when subjected to acompression force by a compression member of a vibratory screeningmachine against the load bar of the vibratory screen assembly. Thescreen assembly may have a concave shape and may be configured todeflect and form a predetermined concave shape when subjected to acompression force by a member of a vibratory screening machine.

A first set of the subgrids may be formed into center support frameassemblies having a first fastener arrangement. A second set of thesubgrids may be formed into a first end support frame assembly having asecond fastener arrangement. A third set of the subgrids may be formedinto a second end support frame assembly having a third fastenerarrangement. The first, second, and third fastener arrangements maysecure the first and second end support frames to the center supportassemblies. A side edge surface of the first end support frame assemblymay form a first end of the screen assembly. A side edge surface of thesecond end support frame arrangement may form a second end of the screenassembly. An end surface of each of the first and second end supportframe assemblies and center support frame assemblies may cumulativelyform a first and a second side surface of the complete screen assembly.The first and second side surfaces of the screen assembly may besubstantially parallel and the first and second end surfaces of thescreen assembly may be substantially parallel and substantiallyperpendicular to the side surfaces of the screen assembly. The sidesurfaces of the screen assembly may include fasteners configured toengage at least one of a binder bar and a load distribution bar. Thesubgrids may include side surfaces such that when individual subgridsare secured together to form the first and second end support frameassemblies and the center support frame assembly that the first andsecond end support frame assemblies and the center support frameassembly each form a concave shape. The subgrids may include sidesurfaces shaped such that when individual subgrids are secured togetherto form the first and second end support frame assemblies and the centersupport frame assembly that the first and second end support frameassemblies and the center support frame assembly each form a convexshape.

The screen elements may be affixed to the subgrids by at least one of amechanical arrangement, an adhesive, heat staking and ultrasonicwelding.

According to an example embodiment of the present disclosure, a screenelement is provided having: a screen element screening surface withscreen surface elements forming a series of screening openings; a pairof substantially parallel end portions; a pair of substantially parallelside edge portions substantially perpendicular to the end portions; afirst screen element support member; a second screen element supportmember orthogonal to the first screen element support member, the firstscreen element support member extending between the end portions andbeing approximately parallel to the side edge portions, the secondscreen element support member extending between the side edge portionsand being approximately parallel to the end portions and substantiallyperpendicular to the side edge portions; a first series of reinforcementmembers substantially parallel to the side edge portions; and a secondseries of reinforcement members substantially parallel to the endportions. The screen surface elements run parallel to the end portions.The end portions, side edge portions, first and second support members,first and second series of reinforcement members structurally stabilizescreen surface elements and screening openings, and the screen elementis a single thermoplastic injection molded piece.

According to an example embodiment of the present disclosure, a screenelement is provided having a screen element screening surface withscreen surface elements forming a series of screening openings; a pairof substantially parallel end portions; and a pair of substantiallyparallel side edge portions substantially perpendicular to the endportions. The screen element is a thermoplastic injection molded piece.

The screen element may also have a first screen element support member;a second screen element support member orthogonal to the first screenelement support member, the first screen element support memberextending between the end portions and being approximately parallel tothe side edge portions, the second screen element support memberextending between the side edge portions and being approximatelyparallel to the end portions; a first series of reinforcement memberssubstantially parallel to the side edge portions; and a second series ofreinforcement members substantially parallel to the end portions. Thescreen surface elements may run parallel to the end portions. In certainembodiments, the screen surface elements may also be configured to runperpendicular to the end portions. The end portions, side edge portions,first and second support members, first and second series ofreinforcement members may structurally stabilize screen surface elementsand screening openings.

The screen element may also have a screen element attachment arrangementmolded integrally with the screen element and configured to mate with asubgrid attachment arrangement. Multiple subgrids may form a screenassembly and the screen assembly may have a continuous screen assemblyscreening surface that includes multiple screen element screeningsurfaces.

According to an example embodiment of the present disclosure, a methodfor fabricating a screen assembly for screening materials is providedthat includes: determining screen assembly performance specificationsfor the screen assembly; determining a screening opening requirement fora screen element based on the screen assembly performancespecifications, the screen element including a screen element screeningsurface having screening openings; determining a screen configurationbased on the screen assembly performance specifications, the screenconfiguration including having the screen elements arranged in at leastone of flat configuration and a nonflat configuration; injection moldingthe screen elements with a thermoplastic material; fabricating a subgridconfigured to support the screen elements, the subgrid having a gridframework with grid openings wherein at least one screen element spansat least one grid opening and is secured to a top surface of thesubgrid, the top surface of each subgrid including at least one of aflat surface and a nonflat surface that receives the screen elements;attaching the screen elements to the subgrids; attaching multiplesubgrid assemblies together to form end screen frames and center screenframes; attaching the end screen frames to the center screen frames toform a screen frame structure; attaching a first binder bar to a firstend of the screen frame structure; and attaching a second binder bar toa second end of the screen frame structure to form the screen assembly,the screen assembly having a continuous screen assembly screeningsurface comprised of multiple screen element screening surfaces.

The screen assembly performance specifications may include at least oneof dimensions, material requirements, open screening area, cut point,and capacity requirements for a screening application. A handle may beattached to the binder bar. A tag may be attached to the binder bar,which tag may include a performance description of the screen assembly.At least one of the screen element and the subgrid may be a singlethermoplastic injection molded piece. The thermoplastic material mayinclude a nanomaterial. The subgrid may include at least one base memberhaving fasteners that mate with fasteners of other base members of othersubgrids and secure the subgrids together. The fasteners may be clipsand clip apertures that snap into place and securely attach the subgridstogether.

According to an example embodiment of the present disclosure, a methodfor fabricating a screen assembly for screening materials is provided byinjection molding a screen element with a thermoplastic material, thescreen element including a screen element screening surface havingscreening openings; fabricating a subgrid that supports the screenelement, the subgrid having a grid framework with grid openings, thescreen element spanning at least one grid opening; securing the screenelement to a top surface of the subgrid; and attaching multiple subgridassemblies together to form the screen assembly, the screen assemblyhaving a continuous screen assembly screening surface made of multiplescreen element screening surfaces. The method may also include attachinga first binder bar to a first end of the screen assembly and attaching asecond binder bar to a second end of the screen assembly. The first andsecond binder bars may bind the subgrids together. The binder bar may beconfigured to distribute a load across the first and second ends of thescreen assembly. The thermoplastic material may include a nanomaterial.

According to an example embodiment of the present disclosure, a methodfor screening a material is provided by attaching a screen assembly to avibratory screening machine, the screen assembly including a screenelement having a series of screening openings forming a screen elementscreening surface and a subgrid including multiple elongated structuralmembers forming a grid framework having grid openings. Screen elementsspan grid openings and are secured to a top surface of the subgrid.Multiple subgrids are secured together to form the screen assembly. Thescreen assembly has a continuous screen assembly screening surfacecomprised of multiple screen element screening surfaces. The screenelement is a single thermoplastic injection molded piece. The materialis screened using the screen assembly.

According to an example embodiment of the present disclosure, a methodfor screening a material is provided including attaching a screenassembly to a vibratory screening machine and forming a top screeningsurface of the screen assembly into a concave shape. The screen assemblyincludes a screen element having a series of screening openings forminga screen element screening surface and a subgrid including multipleelongated structural members forming a grid framework having gridopenings. Screen elements span grid openings and are secured to a topsurface of the subgrid. Multiple subgrids are secured together to formthe screen assembly and the screen assembly has a continuous screenassembly screening surface comprised of multiple screen elementscreening surfaces. The screen element is a single thermoplasticinjection molded piece. The material is screened using the screenassembly.

According to an example embodiment of the present disclosure, a screenassembly is provided, including: a screen element having a firstadhesion arrangement; and a subgrid unit having a second adhesionarrangement. The first adhesion arrangement and the second adhesionarrangement may be different materials. At least one of the firstadhesion arrangement and the second adhesion arrangement is excitablesuch that the screen element and the subgrid may be secured together.The screen element is a single thermoplastic injection molded piece.

The first adhesion arrangement may be a plurality of cavity pockets on abottom surface of the screen element and the second adhesion arrangementmay be a plurality of fusion bars a top surface of the subgrid. Thescreen element is micro molded and has screening openings betweenapproximately 40 microns and approximately 1000 microns. The cavitypockets may be elongated pockets. The fusion bars may have a heightslightly larger than a depth of the cavity pockets. The depth of thecavity pockets may be approximately 0.05 inches and the height of thefusion bars is approximately 0.056 inches. The fusion bars may have awidth slightly smaller than a width of the cavity pockets.

The screen element may include thermoplastic polyurethane. The subgridmay include nylon. The screen assembly may include additional screenelements and subgrids secured together, wherein multiple subgrids aresecured together. The screen element may have a plurality of screeningopenings being elongated slots with a width and a length, the width ofthe screening openings being approximately 43 microns to approximately1000 microns between inner surfaces of each screen surface element. Thescreen element may be attached to the subgrid via laser welding. A weldbetween the screen element and the subgrid may include a mixture ofmaterials from the screen element and the subgrid.

According to an example embodiment of the present disclosure, a screenassembly is provided, including: a screen element including a screenelement screening surface having a series of screening openings; and asubgrid including multiple elongated structural members forming a gridframework having grid openings. The screen element spans at least one ofthe grid openings and is attached to a top surface of the subgrid.Multiple independent subgrids are secured together to form the screenassembly and the screen assembly has a continuous screen assemblyscreening surface having multiple screen element screening surfaces. Thescreen element includes substantially parallel end portions andsubstantially parallel side edge portions substantially perpendicular tothe end portions. The screen element further includes a first screenelement support member and a second screen element support memberorthogonal to the first screen element support member, the first screenelement support member extending between the end portions and beingapproximately parallel to the side edge portions, the second screenelement support member extending between the side edge portions andbeing approximately parallel to the end portions. The screen elementincludes a first series reinforcement members substantially parallel tothe side edge portions, a second series of reinforcement memberssubstantially parallel to the end portions. The screen element screeningsurface includes screen surface elements forming the screening openings.The end portions, side edge portions, first and second support members,first and second series of reinforcement members structurally stabilizescreen surface elements and screening openings. The screen element is asingle thermoplastic injection molded piece. The screen element includesa plurality of pocket cavities on a bottom surface of the screenelement. The subgrid includes a plurality of fusion bars on the topsurface of the subgrid. The plurality of fusion bars are configured tomate with the plurality of pocket cavities.

The screening openings may be elongated slots with a width and a length,the width of the screening openings being approximately 43 microns toapproximately 1000 microns between inner surfaces of each screen surfaceelement. The plurality of fusion bars may have a height slightly largerthan a depth of the plurality of pocket cavities. The height of theplurality of fusion bars may be approximately 0.056 inches. The depth ofthe plurality of pocket cavities may be approximately 0.050 inches. Eachof plurality of pocket cavities may have a width slightly larger than awidth of each of the plurality of fusion bars. The plurality of fusionbars may be configured such that, when melted, a portion of theplurality of fusion bars fills the width of the plurality of pocketcavities. Material of the screen element may be fused with material ofthe subgrid. The screen element may be configured to allow a laser topass through the screen element and contact the plurality of fusionbars. The laser may melts a portion of the plurality of fusion barsfusing the screen element to the subgrid.

The subgrid may be a single thermoplastic injection molded piece. Thescreen element may include a thermoplastic polyurethane material. Thethermoplastic polyurethane may be at least one of a poly-ether basedthermoplastic polyurethane and a polyester based thermoplasticpolyurethane. The subgrid may include a nylon material. The fusion barsmay include at least one of a carbon and a graphite material. Thesubgrid may include a screen element locator arrangement configured tolocate a screen element upon the subgrid. The screen element may includea plurality of tapered counter bores on a top surface of the screenelement along the side edge portions and the end portions betweenlocator apertures of the locator arrangement. The fusion bars and thepocket cavities may be different materials.

The grid framework may include a first and second grid framework forminga first and a second grid opening, the screen elements including a firstand a second screen element. The subgrid may include a ridge portion anda base portion, the first and second grid frameworks include first andsecond angular surfaces that peak at the ridge portion and extenddownwardly from the peak portion to the base portion, wherein the firstand second screen elements span the first and second angular surfaces,respectively. The screen assembly may include a secondary supportframework spanning at least a portion of each grid opening.

According to an exemplary embodiment of the present invention a screenassembly is provided, including: a screen element including a screenelement screening surface having a series of screening openings and aplurality of pocket cavities on a bottom surface of the screen element;and a subgrid including multiple elongated structural members forming agrid framework having grid openings and a plurality of fusion bars on atop surface of the subgrid. The screen element spans at least one gridopening and is secured to the top surface of the subgrid via fusing theplurality of fusion bars to the plurality of pocket cavities. Multiplesubgrids are secured together to form the screen assembly and the screenassembly has a continuous screen assembly screening surface comprised ofmultiple screen element screening surfaces. The screen element is asingle thermoplastic injection molded piece. The screen element inconfigured to allow a laser to pass through the screen element andcontact the plurality of fusion bars.

The screening openings may be elongated slots with a width and a length,the width of the screening openings being approximately 43 microns toapproximately 1000 microns between inner surfaces of each screen surfaceelement. The screening openings may be elongated slots with a width anda length, the width of the screening openings being approximately 70microns to approximately 180 microns between inner surfaces of eachscreen surface element. The screening openings v elongated slots with awidth and a length, the width of the screening openings beingapproximately 43 microns to approximately 106 microns between innersurfaces of each screen surface element. The screening openings may beelongated slots with a width and a length, the width being about 0.044mm to about 4 mm and the length being about 0.088 mm to about 60 mm.

The subgrid may include substantially parallel triangular end pieces,triangular middle pieces substantially parallel to the triangular endpieces, a first and second mid support substantially perpendicular tothe triangular end pieces and extending between the triangular endpieces, a first and second base support substantially perpendicular tothe triangular end pieces and extending between the triangular endpieces and a central ridge substantially perpendicular to the triangularend pieces and extending between the triangular end pieces, a first edgeof the triangular end pieces, the triangular middle pieces, the firstmid support, the first base support and the central ridge form a firsttop surface of the subgrid having a first series of grid openings and asecond edge of the triangular end pieces, the triangular middle pieces,the second mid support, the second base support and the central ridgeform a second top surface of the subgrid having a second series of gridopenings, the first top surface sloping from the central ridge to thefirst base support, the second top surface sloping from the centralridge to the second base support. A first and a second screen elementmay span the first series and second series of grid openings,respectively.

In exemplary embodiments of the present invention, a method offabricating a screen assembly is provided, including: laser welding ascreen element of a first material to a subgrid of a second material;and attaching multiple subgrids together to form the screen assembly.The first material and the second material are different materials. Thefirst material and the second material are fused together at laser weldlocations.

The screen assembly may have a first adhesion arrangement on a bottomsurface of the screen element and the subgrid has a second adhesionarrangement on a top surface of the subgrid. The first adhesionarrangement may be a plurality of pocket cavities and the secondadhesion arrangement is a plurality of fusion bars. The plurality ofpocket cavities may be configured to mate with the plurality of fusionbars.

The method for fabricating a screen assembly may include locating thescreen element upon the subgrid via location apertures in the screenelement and location extensions on a top surface of the subgrid. Themethod for fabricating a screen assembly may include passing a laserthrough the screen element such that it contacts the plurality of fusionbars. The method for fabricating a screen assembly may include melting aportion of the plurality of fusion bars with the laser. The method forfabricating a screen assembly may include melting a portion of the firstmaterial with one of heat produced by the laser and heat transfer fromthe melted portions of the plurality of fusion bars. The method forfabricating a screen assembly may include removing the laser such thatthe melted portion of the first material and the melted portion of thefusion bars mix and return to a solid.

Example embodiments of the present disclosure are described in moredetail below with reference to the appended Figures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an isometric view of a screen assembly, according to anexemplary embodiment of the present invention.

FIG. 1A is an enlarged view of a break out portion of the screenassembly shown in FIG. 1.

FIG. 1B is a bottom isometric view the screen assembly shown in FIG. 1.

FIG. 2 is an isometric top view of a screen element, according to anexemplary embodiment of the present invention.

FIG. 2A is a top view of the screen element shown in FIG. 2.

FIG. 2B is a bottom isometric view of the screen element shown in FIG.2.

FIG. 2C is a bottom view of the screen element shown in FIG. 2.

FIG. 2D is an enlarged top view of a break out portion of the screenelement shown in FIG. 2.

FIG. 3 is a top isometric view of an end subgrid, according to anexemplary embodiment of the present invention.

FIG. 3A is a bottom isometric view of the end subgrid shown in FIG. 3.

FIG. 4 is a top isometric view of a center subgrid, according to anexemplary embodiment of the present invention.

FIG. 4A is a bottom isometric view of the center subgrid shown in FIG.4.

FIG. 5 is a top isometric view of a binder bar, according to anexemplary embodiment of the present invention.

FIG. 5A is a bottom isometric view of the binder bar shown in FIG. 5.

FIG. 6 is an isometric view of a screen subassembly, according to anexemplary embodiment of the present invention.

FIG. 6A is an exploded view of the subassembly shown in FIG. 6.

FIG. 7 is a top view of the screen assembly shown in FIG. 1.

FIG. 7A is an enlarged cross-section of Section A-A of the screenassembly shown in FIG. 7.

FIG. 8 is a top isometric view of a screen assembly partially coveredwith screen elements, according to an exemplary embodiment of thepresent invention.

FIG. 9 is an exploded isometric view of the screen assembly shown inFIG. 1.

FIG. 10 is an exploded isometric view of an end subgrid showing screenelements prior to attachment to the end subgrid, according to anexemplary embodiment of the present invention.

FIG. 10A is an isometric view of the end subgrid shown in FIG. 10 havingthe screen elements attached thereto.

FIG. 10B is a top view of the end subgrid shown in FIG. 10A.

FIG. 10C is a cross-section of Section B-B of the end subgrid shown inFIG. 10A.

FIG. 11 is an exploded isometric view of a center subgrid showing screenelements prior to attachment to the center subgrid, according to anexemplary embodiment of the present invention.

FIG. 11A is an isometric view of the center subgrid shown in FIG. 11having the screen elements attached thereto.

FIG. 12 is an isometric view of a vibratory screening machine havingscreen assemblies with concave screening surfaces installed thereon,according to an exemplary embodiment of the present invention.

FIG. 12A is an enlarged isometric view of the discharge end of thevibratory screening machine shown in FIG. 12.

FIG. 12B is a front view of the vibratory screening machine shown inFIG. 12.

FIG. 13 is an isometric view of a vibratory screening machine with asingle screening surface having screen assemblies with concave screeningsurfaces installed thereon, according to an exemplary embodiment of thepresent invention.

FIG. 13A is a front view of the vibratory screening machine shown inFIG. 13.

FIG. 14 is a front view of a vibratory screening machine having twoseparate concave screening surfaces with preformed screen assembliesinstalled upon the vibratory screening machine, according to anexemplary embodiment of the present invention.

FIG. 15 is a front view of a vibratory screening machine having a singlescreening surface with a preformed screen assembly installed upon thevibratory screening machine, according to an exemplary embodiment of thepresent invention.

FIG. 16 is an isometric view of an end support frame subassembly,according to an exemplary embodiment of the present invention.

FIG. 16A is an exploded isometric view of the end support framesubassembly shown in FIG. 16.

FIG. 17 is an isometric view of a center support frame subassembly,according to an exemplary embodiment of the present invention.

FIG. 17A is an exploded isometric view of the center support framesubassembly shown in FIG. 17.

FIG. 18 is an exploded isometric view of a screen assembly, according toan exemplary embodiment of the present invention.

FIG. 19 is a top isometric view of a flat screen assembly, according toan exemplary embodiment of the present invention.

FIG. 20 is a top isometric view of a convex screen assembly, accordingto an exemplary embodiment of the present invention.

FIG. 21 is an isometric view of a screen assembly having pyramidalshaped subgrids, according to an exemplary embodiment of the presentinvention.

FIG. 21A is an enlarged view of section D of the screen assembly shownin FIG. 21.

FIG. 22 is a top isometric view of a pyramidal shaped end subgrid,according to an exemplary embodiment of the present invention.

FIG. 22A is a bottom isometric view of the pyramidal shaped end subgridshown in FIG. 22.

FIG. 23 is a top isometric view of a pyramidal shaped center subgrid,according to an exemplary embodiment of the present invention.

FIG. 23A is a bottom isometric view of the pyramidal shaped centersubgrid shown in FIG. 23.

FIG. 24 is an isometric view of a pyramidal shaped subassembly,according to an exemplary embodiment of the present invention.

FIG. 24A is an exploded isometric view of the pyramidal shapedsubassembly shown in FIG. 24.

FIG. 24B is an exploded isometric view of a pyramidal shaped end subgridshowing screen elements prior to attachment to the pyramidal shaped endsubgrid.

FIG. 24C is an isometric view of the pyramidal shaped end subgrid shownin FIG. 24B having the screen elements attached thereto.

FIG. 24D is an exploded isometric view of a pyramidal shaped centersubgrid showing screen elements prior to attachment to the pyramidalshaped center subgrid, according to an exemplary embodiment of thepresent invention.

FIG. 24E is an isometric view of the pyramidal shaped center subgridshown in FIG. 24D having the screen elements attached thereto.

FIG. 25 is a top view of a screen assembly having pyramidal shapedsubgrids, according to an exemplary embodiment of the present invention.

FIG. 25A is a cross-section view of Section C-C of the screen assemblyshown in FIG. 25.

FIG. 25B is an enlarged view of Section C-C shown in FIG. 25A.

FIG. 26 is an exploded isometric view of a screen assembly havingpyramidal shaped and flat subassemblies, according to an exemplaryembodiment of the present invention.

FIG. 27 is an isometric view of a vibratory screening machine with twoscreening surfaces having assemblies with concave screening surfacesinstalled thereon wherein the screen assemblies include pyramidal shapedand flat subassemblies, according to an exemplary embodiment of thepresent invention.

FIG. 28 is a top isometric view of a screen assembly having pyramidalshaped and flat subgrids without screen elements, according to anexemplary embodiment of the present invention.

FIG. 29 is a top isometric view of the screen assembly shown in FIG. 28where the subgrids are partially covered with screen elements.

FIG. 30 is a front view of a vibratory screening machine with twoscreening surfaces having assemblies with concave screening surfacesinstalled thereon where the screen assemblies include pyramidal shapedand flat subgrids, according to an exemplary embodiment of the presentinvention.

FIG. 31 is a front view of a vibratory screening machine with a singlescreen surface having an assembly with a concave screening surfaceinstalled thereon where the screen assembly includes pyramidal shapedand flat subgrids, according to an exemplary embodiment of the presentinvention.

FIG. 32 is a front view of a vibratory screening machine with twoscreening surfaces having preformed screen assemblies with flatscreening surfaces installed thereon where the screen assemblies includepyramidal shaped and flat subgrids, according to an exemplary embodimentof the present invention.

FIG. 33 is a front view of a vibratory screening machine with a singlescreening surface having a preformed screen assembly with a flatscreening surface installed thereon where the screen assembly includespyramidal shaped and flat subgrids, according to an exemplary embodimentof the present invention.

FIG. 34 is an isometric view of the end subgrid shown in FIG. 3 having asingle screen element partially attached thereto, according to anexemplary embodiment of the present invention.

FIG. 35 is an enlarged view of break out Section E of the end subgridshown in FIG. 34.

FIG. 36 is an isometric view of a screen assembly having pyramidalshaped subgrids in a portion of the screen assembly, according to anexemplary embodiment of the present invention.

FIG. 37 is a flow chart of a screen assembly fabrication, according toan exemplary embodiment of the present invention.

FIG. 38 is a flow chart of a screen assembly fabrication, according toan exemplary embodiment of the present invention.

FIG. 39 an isometric view of a vibratory screening machine having asingle screen assembly with a flat screening surface installed thereonwith a portion of the vibratory machine cut away showing the screenassembly, according to an exemplary embodiment of the present invention.

FIG. 40 is an isometric top view of an individual screen element,according to an exemplary embodiment of the present invention.

FIG. 40A is an isometric top view of a screen element pyramid, accordingto an exemplary embodiment of the present invention.

FIG. 40B is an isometric top view of four of the screen element pyramidsshown in FIG. 40A.

FIG. 40C is an isometric top view of an inverted screen element pyramid,according to an exemplary embodiment of the present invention.

FIG. 40D is a front view of the screen element shown in FIG. 40C.

FIG. 40E is an isometric top view of a screen element structure,according to an exemplary embodiment of the present invention.

FIG. 40F is a front view of the screen element structure shown in FIG.40E.

FIGS. 41 to 43 are front cross-sectional profile views of screenelements, according to exemplary embodiments of the present invention.

FIG. 44 is an isometric top view of a prescreening structure withprescreen assemblies according to an exemplary embodiment of the presentinvention.

FIG. 44A is an isometric top view of the prescreen assembly shown inFIG. 44, according to an exemplary embodiment of the present invention.

FIG. 45 is a top view of a screen element above a portion of a subgrid,according to an exemplary embodiment of the present invention.

FIG. 45A is an exploded side view of cross section A-A showing thescreen element above the portion of the subgrid of FIG. 45.

FIG. 45B is a side view of cross section A-A of the screen element andthe portion of the subgrid of FIG. 45 prior to attachment of the screenelement to the subgrid, according to an exemplary embodiment of thepresent invention.

FIG. 45C is an enlarged view of section A of FIG. 45B.

FIG. 45D is a side view of cross section A-A of the screen element andthe portion of the subgrid of FIG. 45 after attachment of the screenelement to the subgrid, according to an exemplary embodiment of thepresent invention.

FIG. 45E is an enlarged view of section B of FIG. 45D.

FIG. 46 is side cross section view of a portion of a screen element anda portion of a subgrid, according to an exemplary embodiment of thepresent invention.

FIG. 47 is a top isometric view of a portion of a screen assembly,according to an exemplary embodiment of the present invention.

FIG. 48 is an isometric top view of a screen element, according to anexemplary embodiment of the present invention.

FIG. 48A is a top view of the screen element shown in FIG. 48.

FIG. 48B is a bottom isometric view of the screen element shown in FIG.48.

FIG. 48C is a bottom view of the screen element shown in FIG. 48.

FIG. 49 is a top isometric view of an end subgrid, according to anexemplary embodiment of the present invention.

FIG. 49A is a bottom isometric view of the end subgrid shown in FIG. 49.

FIG. 50 is a top isometric view of a center subgrid, according to anexemplary embodiment of the present invention.

FIG. 50A is a bottom isometric view of the center subgrid shown in FIG.50.

FIG. 51 is an exploded isometric view of an end subgrid showing screenelements prior to attachment to the end subgrid, according to anexemplary embodiment of the present invention.

FIG. 51A is an isometric view of the end subgrid shown in FIG. 51 havingthe screen elements attached thereto.

FIG. 52 is an exploded isometric view of a center subgrid showing screenelements prior to attachment to the center subgrid, according to anexemplary embodiment of the present invention.

FIG. 52A is an isometric view of the center subgrid shown in FIG. 52having the screen elements attached thereto.

FIG. 53 is a top isometric view of a pyramidal shaped end subgrid,according to an exemplary embodiment of the present invention.

FIG. 53A is a bottom isometric view of the pyramidal shaped end subgridshown in FIG. 53.

FIG. 54 is a top isometric view of a pyramidal shaped center subgrid,according to an exemplary embodiment of the present invention.

FIG. 54A is a bottom isometric view of the pyramidal shaped centersubgrid shown in FIG. 54.

FIG. 55 is an exploded isometric view of a pyramidal shaped end subgridshowing screen elements prior to attachment to the pyramidal shaped endsubgrid, according to an exemplary embodiment of the present invention.

FIG. 55A is an isometric view of the pyramidal shaped end subgrid shownin FIG. 55 having the screen elements attached thereto.

FIG. 56 is an exploded isometric view of a pyramidal shaped centersubgrid showing screen elements prior to attachment to the pyramidalshaped center subgrid, according to an exemplary embodiment of thepresent invention.

FIG. 56A is an isometric view of the pyramidal shaped center subgridshown in FIG. 56 having the screen elements attached thereto.

FIG. 57 is an isometric view of the end subgrid shown in FIG. 50 havinga singles screen element partially attached thereto, according to anexemplary embodiment of the present invention.

FIG. 57A is an enlarged view of section A of the end subgrid shown inFIG. 57.

DETAILED DESCRIPTION

Like reference characters denote like parts in several drawings.

Embodiments of the present invention provide a screen assembly thatincludes injection molded screen elements that are mated to a subgrid.Multiple subgrids are securely fastened to each other to form thevibratory screen assembly, which has a continuous screening surface andis configured for use on a vibratory screening machine. The entirescreen assembly structure is configured to withstand rigorous loadingconditions encountered when mounted and operated on a vibratoryscreening machine. Injection molded screen elements provide for manyadvantages in screen assembly manufacturing and vibratory screeningapplications. In certain embodiments of the present invention, screenelements are injection molded using a thermoplastic material. In certainembodiments of the present invention, screen elements may have a firstadhesion arrangement configured to mate with a second adhesionarrangement on a subgrid. The first and second adhesion arrangements mayinclude different materials and may be configured such that screenelements may be fused to the subgrid via laser welding. The firstadhesion arrangement may be a plurality of pocket cavities and thesecond adhesion arrangement may be a plurality of fusion bars, which maybe configured to melt when subjected to a laser. Screen elements mayinclude a thermoplastic polyurethane, which may be polyester based orpoly-ether based. Embodiments of the present invention include screenelements secured to subgrids via a hardened mixture of separatematerials. Embodiments of the present invention include methods offabricating a screen assembly by fusing screen elements to subgrids vialaser welding and attaching multiple subgrids together to form thescreen assembly.

Embodiments of the present invention provide injection molded screenelements that are of a practical size and configuration for manufactureof vibratory screen assemblies and for use in vibratory screeningapplications. Several important considerations have been taken intoaccount in the configuration of individual screen elements. Screenelements are provided that: are of an optimal size (large enough forefficient assembly of a complete screen assembly structure yet smallenough to injection mold (micromold in certain embodiments) extremelysmall structures forming screening openings while avoiding freezing(i.e., material hardening in a mold before completely filling themold)); have optimal open screening area (the structures forming theopenings and supporting the openings are of a minimal size to increasethe overall open area used for screening while maintaining, in certainembodiments, very small screening openings necessary to properlyseparate materials to a specified standard); have durability andstrength, can operate in a variety of temperature ranges; are chemicallyresistant; are structural stable; are highly versatile in screenassembly manufacturing processes; and are configurable in customizableconfigurations for specific applications.

Embodiments of the present invention provide screen elements that arefabricated using extremely precise injection molding. The larger thescreen element the easier it is to assemble a complete vibratoryscreening assembly. Simply put, the fewer pieces there are to puttogether. However, the larger the screen element the more difficult itis to injection mold extremely small structures, i.e. the structuresforming the screening openings. It is important to minimize the size ofthe structures forming the screening openings so as to maximize thenumber of screening openings on an individual screen element and therebyoptimize the open screening area for the screening element and thus theoverall screen assembly. In certain embodiments, screen elements areprovided that are large enough (e.g., one inch by one inch, one inch bytwo inches, two inches by three inches, etc.) to make it practical toassemble a complete screen assembly screening surface (e.g., two feet bythree feet, three feet by four feet, etc.). The relatively “small size”(e.g., one inch by one inch, one inch by two inches, two inches by threeinches, etc.) is fairly large when micromolding extremely smallstructural members (e.g., structural members as small as 43 microns).The larger the size of the overall screen element and the smaller thesize of the individual structural members forming the screening openingsthe more prone the injection molding process is to errors such asfreezing. Thus, the size of the screen elements must be practical forscreen assembly manufacture while at the same time small enough toeliminate problems such as freezing when micromolding extremely smallstructures. Sizes of screening elements may vary based on the materialbeing injection molded, the size of the screening openings required andthe overall open screening area desired.

Open screening area is a critical feature of vibratory screenassemblies. The average usable open screening area (i.e., actual openarea after taking into account the structural steel of support membersand bonding materials) for traditional 100 mesh to 200 mesh wire screenassemblies may be in the range of 16%. Specific embodiments of thepresent invention (e.g., screening assemblies with constructionsdescribed herein and having 100 mesh to 200 mesh screen openings)provide screen assemblies in the same range having a similar actual openscreening areas. Traditional screens, however, blind fairly quickly inthe field which results in the actual opening screening area beingreduced fairly quickly. It is not uncommon for traditional metal screensto blind within the first 24 hours of use and to have the actual openscreening area reduced by 50%. Traditional wire assemblies alsofrequently fail as a result of wires being subjected to vibratory forceswhich place bending loads of the wires. Injection molded screenassemblies, according to embodiments of the present invention, incontrast, are not subject to extensive blinding (thereby maintaining arelatively constant actual open screening area) and rarely fail becauseof the structural stability and configuration of the screen assembly,including the screen elements and subgrid structures. In fact, screenassemblies according to embodiments of the present invention haveextremely long lives and may last for long periods of time under heavingloading. Screen assemblies according to the present invention have beentested for months under rigorous conditions without failure or blindingwhereas traditional wire assemblies were tested under the sameconditions and blinded and failed within days. As more fully discussedherein, traditional thermoset type assemblies could not be used in suchapplications.

In embodiments of the present invention a thermoplastic is used toinjection mold screen elements. As opposed to thermoset type polymers,which frequently include liquid materials that chemically react and cureunder temperature, use of thermoplastics is often simpler and may beprovided, e.g., by melting a homogeneous material (often in the form ofsolid pellets) and then injection molding the melted material. Not onlyare the physical properties of thermoplastics optimal for vibratoryscreening applications but the use of thermoplastic liquids provides foreasier manufacturing processes, especially when micromolding parts asdescribed herein. The use of thermoplastic materials in the presentinvention provides for excellent flexure and bending fatigue strengthand is ideal for parts subjected to intermittent heavy loading orconstant heavy loading as is encountered with vibratory screens used onvibratory screening machines. Because vibratory screening machines aresubject to motion, the low coefficient of friction of the thermoplasticinjection molded materials provides for optimal wear characteristics.Indeed, the wear resistance of certain thermoplastics is superior tomany metals. Further, use of thermoplastics as described herein providesan optimal material when making “snap-fits” due to its toughness andelongation characteristics. The use of thermoplastics in embodiments ofthe present invention also provides for resistance to stress cracking,aging and extreme weathering. The heat deflection temperature ofthermoplastics is in the range of 200° F. With the addition of glassfibers, this will increase to approximately 250° F. to approximately300° F. or greater and increase rigidity, as measured by FlexuralModulus, from approximately 400,000 PSI to over approximately 1,000,000PSI. All of these properties are ideal for the environment encounteredwhen using vibratory screens on vibratory screening machines under thedemanding conditions encounter in the field.

Embodiments of the present invention may incorporate various materialsinto subgrid units and/or the screen elements depending on the desiredproperties of the embodiments. Thermoplastic polyurethane (TPU) may beincorporated into embodiments of the present invention (e.g., screenelements), providing elasticity, transparency, and resistance to oil,grease, and abrasion. TPU also has high shear strength. These propertiesof TPU are beneficial when applied to embodiments of the presentinvention, which are subjected to high vibratory forces, abrasivematerials and high load demands. Different types of TPU may beincorporated into embodiments depending on the material being screened.For example, polyester-based TPUs may be incorporated into screenassemblies used for oil and/or gas screening because the esters providesuperior abrasion resistance, oil resistance, mechanical integrity,chemical resistance and adhesion strength. Poly-ether based TPUs may beincorporated into mining applications where hydrolysis resistance (aproperty of ether based TPUs) is important. Para-phenylene disocyanate(PPDI) may be incorporated into embodiments of the present invention.PPDI may provide high performance properties in a variety of screeningapplications. Materials for embodiments of the present invention may beselected or determined based upon a variety of factors, includingperformance properties of each material and costs associated with usingthe materials.

In embodiments of the present invention, materials for a screen elementmay be selected to have high temperature tolerance, chemical resistance,hydrolytic resistance, and/or abrasion resistance. Screen elements mayincorporate materials, such as TPUs, providing the screen elements witha clear appearance. Clear screen elements may allow for efficient lasertransmission through the screen elements for laser welding purposes.Subgrid materials may be different than the screen element material. Inembodiments of the present invention, subgrids may be nylon. Subgridsmay incorporate carbon or graphite. Different materials between screenelements and subgrids may be secured to each other via laser welding,which may provide a much stronger adhesion between the screen elementsand the subgrids than alternative attachment methods. The strongerattachment of the screen element to the subgrid provides improvedperformance of the screen assemblies when subjected to the highvibratory forces of vibratory screening machines and the abrasive forcesthat occur on the surfaces of the screen elements during screening ofmaterials.

FIG. 1 illustrates a screen assembly 10 for use with vibratory screeningmachines. Screen assembly 10 is shown having multiple screen elements 16(See, e.g., FIGS. 2 and 2A-2D) mounted on subgrid structures. Thesubgrid structures include multiple independent end subgrid units 14(See, e.g., FIG. 3) and multiple independent center subgrid units 18(See, e.g., FIG. 4) that are secured together to form a grid frameworkhaving grid openings 50. Each screen element 16 spans four grid openings50. Although screen element 16 is shown as a unit covering four gridopenings, screen elements may be provided in larger or smaller sizedunits. For example, a screen element may be provided that isapproximately one-fourth the size of screen element 16 such that itwould span a single grid opening 50. Alternatively, a screen element maybe provided that is approximately twice the size of screen element 16such that it would span all eight grid openings of subgrid 14 or 18.Subgrids may also be provided in different sizes. For example, subgridunits may be provided that have two grid openings per unit or one largesubgrid may be provided for the overall structure, i.e., a singlesubgrid structure for the entire screen assembly. In FIG. 1, multipleindependent subgrids 14 and 18 are secured together to form the screenassembly 10. Screen assembly 10 has a continuous screen assemblyscreening surface 11 that includes multiple screen element screeningsurfaces 13. Each screen element 16 is a single thermoplastic injectionmolded piece.

FIG. 1A is an enlarged view of a portion of the screen assembly 10having multiple end subgrids 14 and center subgrids 18. As discussedbelow, the end subgrids 14 and center subgrids 18 may be securedtogether to form the screen assembly. Screen elements 16 are shownattached to the end subgrids 14 and center subgrids 18. The size of thescreen assembly may be altered by attaching more or less subgridstogether to form the screen assembly. When installed in a vibratoryscreening machine, material may be fed onto the screen assembly 10. See,e.g., FIGS. 12, 12A, 12B, 13, 13A, 14, and 15. Material smaller than thescreen openings of the screen element 16, passes through the openings inscreening element 16 and through the grid openings 50 thereby separatingthe material from that which is too big to pass through the screenopenings of the screen elements 16.

FIG. 1B shows a bottom view of the screen assembly 10 such that the gridopenings 50 may be seen below the screen elements. Binder bars 12 areattached to sides of the grid framework. Binder bars 12 may be attachedto lock subassemblies together creating the grid framework. Binder bars12 may include fasteners that attach to fasteners on side members 38 ofsubgrid units (14 and 18) or fasteners on base member 64 of pyramidalsubgrid units (58 and 60). Binder bars 12 may be provided to increasethe stability of the grid framework and may distribute compression loadsif the screen assembly is mounted to a vibratory screening machine usingcompression, e.g., using compression assemblies as described in U.S.Pat. No. 7,578,394 and U.S. patent application Ser. No. 12/460,200.Binder bars may also be provided that include U-shaped members or fingerreceiving apertures, for undermount or overmount tensioning onto avibratory screening machine, e.g., see mounting structures described inU.S. Pat. Nos. 5,332,101 and 6,669,027. The screen elements and subgridsare securely attached together, as described herein, such that, evenunder tensioning, the screen assembly screening surface and screenassembly maintain their structural integrity.

The screen assembly shown in FIG. 1 is slightly concave, i.e., thebottom and top surfaces of the screen assembly have a slight curvature.Subgrids 14 and 18 are fabricated such that when they are assembledtogether this predetermined curvature is achieved. Alternatively, ascreen assembly may be flat or convex (see, e.g., FIGS. 19 and 20). Asshown in FIGS. 12, 12A, 13, and 13A, screen assembly 10 may be installedupon a vibratory screening machine having one or more screeningsurfaces. In one embodiment, screen assembly 10 may be installed upon avibratory screening machine by placing screen assembly 10 on thevibratory screening machine such that the binder bars contact end orside members of the vibratory screening machine. Compression force isthen applied to binder bar 12. Binder bars 12 distribute the load fromthe compression force to the screen assembly. The screen assembly 10 maybe configured such that it flexes and deforms into a predeterminedconcave shape when compression force is applied to binder bar 12. Theamount of deformation and range of concavity may vary according to use,compression forced applied, and shape of the bed support of thevibratory screening machine. Compressing screen assembly 10 into aconcave shape when installed in a vibratory screening machine providesmany benefits, e.g., easy and simple installation and removal, capturingand centering of materials to be screened, etc. Further benefits areenumerated in U.S. Pat. No. 7,578,394. Centering of material streams onscreen assembly 10 prevents the material from exiting the screeningsurface and potentially contaminating previously segregated materialsand/or creating maintenance concerns. For larger material flow volumes,screen assembly 10 may be placed in greater compression, therebyincreasing the amount of arc of the screen assembly 10. The greater theamount of arc in screen assembly 10 allows for greater retainingcapability of material by screen assembly 10 and prevention of overspilling of material off edges of the screen assembly 10. Screenassembly 10 may also be configured to deform into a convex shape undercompression or remain substantially flat under compression or clamping.Incorporating binder bars 12 into the screen assembly 10 allows for acompression load from a vibratory screening machine to be distributedacross the screen assembly 10. Screen assembly 10 may include guidenotches in the binder bars 12 to help guide the screen assembly 10 intoplace when installed upon a vibratory screening machine having guides.Alternatively, the screen assembly may be installed upon a vibratoryscreening machine without binder bars 12. In the alternative embodiment,guide notches may be included in subgrid units. U.S. patent applicationSer. No. 12/460,200 is incorporated herein by reference and anyembodiments disclosed therein may be incorporated into embodiments ofthe present invention described herein.

FIG. 2 shows a screen element 16 having substantially parallel screenelement end portions 20 and substantially parallel screen element sideportions 22 that are substantially perpendicular to the screen elementend portions 20. The screen element screening surface 13 includessurface elements 84 running parallel to the screen element end portions20 and forming screening openings 86. See FIG. 2D. Surface elements 84have a thickness T, which may vary depending on the screeningapplication and configuration of the screening openings 86. T may be,e.g., approximately 43 microns to approximately 100 microns depending onthe open screening area desired and the width W of screening openings86. The screening openings 86 are elongated slots having a length L anda width W, which may be varied for a chosen configuration. The width maybe a distance of approximately 43 microns to approximately 2000 micronsbetween inner surfaces of each screen surface element 84. The screeningopenings are not required to be rectangular but may be thermoplasticinjection molded to any shape suitable to a particular screeningapplication, including approximately square, circular and/or oval. Forincreased stability, the screen surface elements 84 may include integralfiber materials which may run substantially parallel to end portions 20.The fiber may be an aramid fiber (or individual filaments thereof), anaturally occurring fiber or other material having a relatively hightensile strength. U.S. Pat. No. 4,819,809 and U.S. patent applicationSer. No. 12/763,046 are incorporated herein by reference and, asappropriate, the embodiments disclosed therein may be incorporated intothe screen assemblies disclosed herein.

The screen element 16 may include attachment apertures 24 configuredsuch that elongated attachment members 44 of a subgrid may pass throughthe attachment apertures 24. The attachment apertures 24 may include atapered bore that may be filled when a portion of the elongatedattachment member 44 above the screening element screening surface ismelted fastening screen element 16 to the subgrid. Alternatively, theattachment apertures 24 may be configured without a tapered boreallowing formation of a bead on the screening element screening surfacewhen a portion of an elongated attachment member 44 above a screeningelement screening surface is melted fastening the screen element to thesubgrid. Screen element 16 may be a single thermoplastic injectionmolded piece. Screen element 16 may also be multiple thermoplasticinjection molded pieces, each configured to span one or more gridopenings. Utilizing small thermoplastic injection molded screen elements16, which are attached to a grid framework as described herein, providesfor substantial advantages over prior screen assemblies. Thermoplasticinjection molding screen elements 16 allow for screening openings 86 tohave widths W as small as approximately 43 microns. This allows forprecise and effective screening. Arranging the screen elements 16 onsubgrids, which may also be thermoplastic injection molded, allows foreasy construction of complete screen assemblies with very fine screeningopenings. Arranging the screen elements 16 on subgrids also allows forsubstantial variations in overall size and/or configuration of thescreen assembly 10, which may be varied by including more or lesssubgrids or subgrids having different shapes. Moreover, a screenassembly may be constructed having a variety of screening opening sizesor a gradient of screening opening sizes simply by incorporating screenelements 16 with the different size screening openings onto subgrids andjoining the subgrids in the desired configuration.

FIG. 2B and FIG. 2C show a bottom of the screen element 16 having afirst screen element support member 28 extending between the endportions 20 and being substantially perpendicular to the end portions20. FIG. 2B also shows a second screen element support member 30orthogonal to the first screen element support member 28 extendingbetween the side edge portions 22 being approximately parallel to theend portions 20 and substantially perpendicular to the side portions 22.The screen element may further include a first series reinforcementmembers 32 substantially parallel to the side edge portions 22 and asecond series of reinforcement members 34 substantially parallel to theend portions 20. The end portions 20, the side edge portions 22, thefirst screen element support member 28, the second screen elementsupport member 30, the first series reinforcement members 32, and thesecond series of reinforcement members 34 structurally stabilize thescreen surface elements 84 and screening openings 86 during differentloadings, including distribution of a compression force and/or vibratoryloading conditions.

FIG. 3 and FIG. 3A illustrate an end subgrid 14 unit. The end subgridunit 14 includes parallel subgrid end members 36 and parallel subgridside members 38 substantially perpendicular to the subgrid end members36. The end subgrid unit 14 has fasteners along one subgrid end member36 and along the subgrid side members 38. The fasteners may be clips 42and clip apertures 40 such that multiple subgrid units 14 may besecurely attached together. The subgrid units may be secured togetheralong their respective side members 38 by passing the clip 42 into theclip aperture 40 until extended members of the clip 42 extend beyondclip aperture 40 and subgrid side member 38. As the clip 42 is pushedinto the clip aperture 40, the clip's extended members will be forcedtogether until a clipping portion of each extended member is beyond thesubgrid side member 38 allowing the clipping portions to engage aninterior portion of the subgrid side member 38. When the clippingportions are engaged into the clip aperture, subgrid side members of twoindependent subgrids will be side by side and secured together. Thesubgrids may be separated by applying a force to the clip's extendedmembers such that the extended members are moved together allowing forthe clipping portions to pass out of the clip aperture. Alternatively,the clips 42 and clip apertures 40 may be used to secure subgrid endmember 36 to a subgrid end member of another subgrid, such as a centersubgrid (FIG. 4). The end subgrid may have a subgrid end member 36 thatdoes not have any fasteners. Although the fasteners shown in drawingsare clips and clip apertures, alternative fasters and alternative formsof clips and apertures may be used, including other mechanicalarrangements, adhesives, etc.

Constructing the grid framework from subgrids, which may besubstantially rigid, creates a strong and durable grid framework andscreen assembly 10. Screen assembly 10 is constructed so that it canwithstand heavy loading without damage to the screening surface andsupporting structure. For example, the pyramidal shaped grid frameworksshown in FIGS. 22 and 23 provide a very strong pyramid base frameworkthat supports individual screen elements capable of very fine screening,having screening openings as small as 43 microns. Unlike the pyramidalscreen assembly embodiment of the present invention described herein,existing corrugated or pyramid type wire mesh screen assemblies arehighly susceptible to damage and/or deformation under heavy loading.Thus, unlike current screens, the present invention provides for screenassemblies having very small and very precise screening openings whilesimultaneously providing substantial structural stability and resistanceto damage thereby maintaining precision screening under a variety ofload burdens. Constructing the grid framework from subgrids also allowsfor substantial variation in the size, shape, and/or configuration ofthe screen assembly by simply altering the number and/or type ofsubgrids used to construct the grid framework.

End subgrid unit 14 includes a first subgrid support member 46 runningparallel to subgrid side members 38 and a second subgrid support member48 orthogonal to the first subgrid support member 46 and perpendicularto the subgrid side members 38. Elongated attachment members 44 may beconfigured such that they mate with the screen element attachmentapertures 24. Screen element 16 may be secured to the subgrid 14 viamating the elongated attachment members 44 with screen elementattachment apertures 24. A portion of elongated attachment member 44 mayextend slightly above the screen element screening surface when thescreen element 16 is attached to the end subgrid 14. The screen elementattachment apertures 24 may include a tapered bore such that a portionof the elongated attachment members 44 extending above the screenelement screening surface may be melted and fill the tapered bore.Alternatively, screen element attachment apertures 24 may be without atapered bore and the portion of the elongated attachment membersextending above the screening surface of the screening element 16 may beconfigured to form a bead on the screening surface when melted. SeeFIGS. 34 and 35. Once attached, the screen element 16 will span at leastone grid opening 50. Materials passing through the screening openings 86will pass through grid opening 50. The arrangement of elongatedattachment members 44 and the corresponding arrangement of screenelement attachment apertures 24 provide a guide for attachment of screenelements 16 to subgrids simplifying assembly of subgrids. The elongatedattachment members 44 pass through the screen element attachmentapertures 24 guiding the screen element into correct placement on thesurface of the subgrid. Attachment via elongated attachment members 44and screen element attachment apertures 24 further provides a secureattachment to the subgrid and strengthens the screening surface of thescreen assembly 10.

FIG. 4 shows a center subgrid 18. As shown in FIG. 1 and FIG. 1A, thecenter subgrid 18 may be incorporated into a screen assembly. The centersubgrid 18 has clips 42 and clip apertures 40 on both subgrid endmembers 36. The end subgrid 14 has clips 42 and clip apertures 40 ononly one of two subgrid end members 36. Center subgrids 18 may besecured to other subgrids on each of its subgrid end members and subgridside members.

FIG. 5 shows a top view of binder bar 12. FIG. 5A shows a bottom view ofbinder bar 12. Binder bars 12 include clips 42 and clip apertures 40such that binder bar 12 may be clipped to a side of an assembly ofscreen panels (see FIG. 9). As with subgrids, fasteners on the binderbar 12 are shown as clips and clip apertures but other fasteners may beutilized to engage fasteners of the subgrids. Handles may be attached tobinder bars 12 (see, e.g., FIG. 7) which may simplify transportation andinstallation of a screen assembly. Tags and/or labels may also beattached to binder bars. As discussed above, binder bars 12 may increasethe stability of the grid framework and may distribute compression loadsof a vibratory screening machine if the screen assembly is placed undercompression as shown in U.S. Pat. No. 7,578,394 and U.S. patentapplication Ser. No. 12/460,200.

The screening members, screening assemblies and parts thereof, includingconnecting members/fasteners as described herein, may includenanomaterial dispersed therein for improved strength, durability andother benefits associated with the use of a particular nanomaterial orcombination of different nanomaterials. Any suitable nanomaterial may beused, including, but not limited to nanotubes, nanofibers and/orelastomeric nanocomposites. The nanomaterial may be dispersed in thescreening members and screening assemblies and parts thereof in varyingpercentages, depending on the desired properties of the end product. Forexample, specific percentages may be incorporated to increase memberstrength or to make a screening surface wear resistant. Use of athermoplastic injection molded material having nanomaterials dispersedtherein may provide for increased strength while using less material.Thus, structural members, include subgrid framework supports and screenelement supporting members may be made smaller and stronger and/orlighter. This is particularly beneficial when fabricating relativelysmall individual components that are built into a complete screenassembly. Also, instead of producing individual subgrids that cliptogether, one large grid structure having nanomaterials dispersedtherein, may be fabricated that is relatively light and strong.Individual screen elements, with or without nanomaterials, may then beattached to the single complete grid framework structure. Use ofnanomaterials in a screen element will provide increased strength whilereducing the weight and size of the element. This may be especiallyhelpful when injection molding screen elements having extremely smallopenings as the openings are supported by the surroundingmaterials/members. Another advantage to incorporating nanomaterials intothe screen elements is an improved screening surface that is durable andresistant to wear. Screen surfaces tend to wear out through heavy useand exposure to abrasive materials and use of a thermoplastic and/or athermoplastic having abrasive resistant nanomaterials, provides for ascreening surface with a long life.

FIG. 6 shows a subassembly 15 of a row of subgrid units. FIG. 6A is anexploded view of the subassembly in FIG. 6 showing individual subgridsand direction of attachment to each other. The subassembly includes twoend subgrid units 14 and three center subgrid units 18. The end subgridunits 14 form the ends of the subassembly while the center subgrid units18 are used to join the two end subgrid units 14 via connections betweenthe clips 42 and clip apertures 40. The subgrid units shown in FIG. 6are shown with attached screen elements 16. By fabricating the screenassembly from subgrids and into the subassembly, each subgrid may beconstructed to a chosen specification and the screen assembly may beconstructed from multiple subgrids in a configuration required for thescreening application. The screen assembly may be quickly and simplyassembled and will have precise screening capabilities and substantialstability under load pressures. Because of the structure configurationof the grid framework and screen elements 16, the configuration ofmultiple individual screen elements forming the screening surface of thescreen assembly 10 and the fact that the screen elements 16 arethermoplastic injection molded, the openings in screen elements 16 arerelatively stable and maintain their opening sizes for optimal screeningunder various loading conditions, including compression loads andconcavity deflections and tensioning.

FIG. 7 shows a screen assembly 10 with binder bars 12 having handlesattached to the binder bars 12. The screen assembly is made up ofmultiple subgrid units secured to each other. The subgrid units havescreen elements 16 attached to their top surfaces. FIG. 7A is across-section of Section A-A of FIG. 7 showing individual subgridssecured to screen elements forming a screening surface. As reflected inFIG. 7A, the subgrids may have subgrid support members 48 configuredsuch that screen assembly has a slightly concave shape when the subgridsupport members 48 are fastened to each other via clips 42 and clipapertures 40. Because the screen assembly is constructed with a slightlyconcave shape it may be configured to deform to a desired concavity uponapplication of a compression load without having to guide the screenassembly into a concave shape. Alternatively, the subgrids may beconfigured to create a slightly convex screen assembly or asubstantially flat screen assembly.

FIG. 8 is a top isometric view of a screen assembly partially coveredwith screen elements 16. This figure shows end subgrid units 14 andcenter subgrid units 18 secured to form a screen assembly. The screeningsurface may be completed by attaching screen elements 16 to theuncovered subgrid units shown in the figure. Screen elements 16 may beattached to individual subgrids prior to construction of the gridframework or attached to subgrids after subgrids have been fastened toeach other into the grid framework.

FIG. 9 is an exploded isometric view of the screen assembly shown inFIG. 1. This figure shows eleven subassemblies being secured to eachother via clips and clip apertures along subgrid end members of subgridunits in each subassembly. Each subassembly has two end subgrid units 14and three center subgrid units 18. Binder bars 12 are clipped at eachside of the assembly. Different size screen assemblies may be createdusing different numbers of subassemblies or different numbers of centersubgrid units in each subassembly. An assembled screen assembly has acontinuous screen assembly screening surface made up of multiple screenelement screening surfaces.

FIGS. 10 and 10A illustrate attachment of screen elements 16 to endsubgrid unit 14, according to an exemplary embodiment of the presentinvention. Screen elements 16 may be aligned with end subgrid unit 14via the elongated attachment members 44 and the screen elementattachment apertures 24 such that the elongated 20 attachment members 44pass through the screen element attachment apertures 24 and extendslightly beyond the screen element screening surface. The elongatedattachment members 44 may be melted to fill the tapered bores of thescreen element attachment apertures 24 or, alternatively, to form beadsupon the screen element screening surface, securing the screen element16 to the subgrid unit 14. Attachment via elongated attachment members44 and screen element attachment apertures 24 is only one embodiment ofthe present invention. Alternatively, screen element 16 may be securedto end subgrid unit 14 via adhesive, fasteners and fastener apertures,laser welding, etc. Although shown having two screen elements for eachsubgrid, the present invention includes alternate configurations of onescreen element per subgrid, multiple screen elements per subgrid, onescreen element per subgrid opening, or having a single screen elementcover multiple subgrids. The end subgrid 14 may be substantially rigidand may be formed as a single thermoplastic injection molded piece.

FIG. 10B is a top view of the end subgrid unit shown in FIG. 10A withscreen elements 16 secured to the end subgrid. FIG. 10C is an enlargedcross-section of Section B-B of the end subgrid unit in FIG. 10B. Screenelement 16 is placed upon the end subgrid unit such that elongatedattachment member 44 passes through the attachment aperture and beyond ascreening surface of the screen element. The portion of the elongatedattachment member 44 passing through the attachment aperture and beyondthe screening surface of the screen element may be melted to attach thescreen element 16 to the end subgrid unit as described above.

FIG. 11 and FIG. 11A illustrate attachment of screen elements 16 tocenter subgrid unit 18, according to an exemplary embodiment of thepresent invention. Screen elements 16 may be aligned with center subgridunit 18 via the elongated attachment members 44 and the screen elementattachment apertures 24 such that the elongated attachment members 44pass through the screen element attachment apertures 24 and extendslightly beyond the screen element screening surface. The elongatedattachment members 44 may be melted to fill the tapered bores of thescreen element attachment apertures 24 or, alternatively, to form beadsupon the screen element screening surface, securing the screen element16 to center subgrid unit 18. Attachment via elongated attachmentmembers 44 and screen element attachment apertures 24 is only oneembodiment of the present invention. Alternatively, screen element 16may be secured to center subgrid unit 14 via adhesive, fasteners andfastener apertures, etc. Although shown having two screen elements foreach subgrid, the present invention includes alternate configurations ofone screen element per subgrid, one screen element per subgrid opening,multiple screen elements per subgrid, or having a single screen elementcover multiple subgrid units. The center subgrid unit 18 may besubstantially rigid and may be a single thermoplastic injection moldedpiece.

FIGS. 12 and 12A show screen assemblies 10 installed on a vibratoryscreening machine having two screening surfaces. The vibratory screeningmachine may have compression assemblies on side members of the vibratoryscreening machine, as shown in U.S. Pat. No. 7,578,394. A compressionforce may be applied to a binder bar or a side member of the screenassembly such that the screen assembly deflects downward into a concaveshape. A bottom side of the screen assembly may mate with a screenassembly mating surface of the vibratory screening machine as shown inU.S. Pat. No. 7,578,394 and U.S. patent application Ser. No. 12/460,200.The vibratory screening machine may include a center wall memberconfigured to receive a binder bar of a side member of the screenassembly opposite of the side member of the screen assembly receivingcompression. The center wall member may be angled such that acompression force against the screen assembly deflects the screenassembly downward. The screen assembly may be installed in the vibratoryscreening machine such that it is configured to receive material forscreening. The screen assembly may include guide notches configured tomate with guides of the vibratory screening machine such that the screenassembly may be guided into place during installation and may includeguide assembly configurations as shown in U.S. patent application Ser.No. 12/460,200.

FIG. 12B is a front view of the vibratory screening machine shown inFIG. 12. FIG. 12B shows screen assemblies 10 installed upon thevibratory screening machine with compression applied to deflect thescreen assemblies downward into a concave shape. Alternatively, thescreen assembly may be preformed in a predetermined concave shapewithout compression force.

FIGS. 13 and 13A show installations of screen assembly 10 in a vibratoryscreening machine having a single screening surface. The vibratoryscreening machine may have a compression assembly on a side member ofthe vibratory screening machine. Screen assembly 10 may be placed intothe vibratory screening machine as shown. A compression force may beapplied to a binder bar or side member of the screen assembly such thatthe screen assembly deflects downward into a concave shape. A bottomside of the screen assembly may mate with a screen assembly matingsurface of the vibratory screening machine as shown in U.S. Pat. No.7,578,394 and U.S. patent application Ser. No. 12/460,200. The vibratoryscreening machine may include a side member wall opposite of thecompression assembly configured to receive a binder bar or a side memberof the screen assembly. The side member wall may be angled such that acompression force against the screen assembly deflects the screenassembly downward. The screen assembly may be installed in the vibratoryscreening machine such that it is configured to receive material forscreening. The screen assembly may include guide notches configured tomate with guides of the vibratory screening machine such that the screenassembly may be guided into place during installation.

FIG. 14 is a front view of screen assemblies 52 installed upon avibratory screening machine having two screening surfaces, according toan exemplary embodiment of the present invention. Screen assembly 52 isan alternate embodiment where the screen assembly has been preformed tofit into the vibratory screening machine without applying a load to thescreen assembly, i.e., screen assembly 52 includes a bottom portion 52Athat is formed such that it mates with a bed 83 of the vibratoryscreening machine. The bottom portion 52A may be formed integrally withscreen assembly 52 or maybe a separate piece. Screen assembly 52includes similar features as screen assembly 10, including subgrids andscreen elements but also includes bottom portion 52A that allows it tofit onto bed 83 without being compressed into a concave shape. Ascreening surface of screen assembly 52 may be substantially flat,concave or convex. Screen assembly 52 may be held into place by applyinga compression force to a side member of screen assembly 52. A bottomportion of screen assembly 52 may be preformed to mate with any type ofmating surface of a vibratory screening machine.

FIG. 15 is a front view of screen assembly 53 installed upon a vibratoryscreening machine having a single screening surface, according to anexemplary embodiment of the present invention. Screen assembly 53 hassimilar features of screen assembly 52 described above, including abottom portion 53A that is formed such that it mates with a bed 87 ofthe vibratory screening machine.

FIG. 16 shows an end support frame subassembly and FIG. 16A shows anexploded view of the end support frame subassembly shown in FIG. 16. Theend support frame subassembly shown in FIG. 16 incorporates eleven endsubgrid units 14. Alternate configurations having more or less endsubgrid units may be utilized. The end subgrid units 14 are secured toeach other via clips 42 and clip apertures 40 along side members of theend subgrid units 14. FIG. 16A shows attachment of individual endsubgrid units such that the end support frame subassembly is created. Asshown, the end support frame subassembly is covered in screen elements16. Alternatively, the end support frame subassembly may be constructedfrom end subgrids prior to attachment of screen elements or partiallyfrom pre-covered subgrid units and partially from uncovered subgridunits.

FIG. 17 shows a center support frame assembly and FIG. 17A shows anexploded view of the center support frame subassembly shown in FIG. 17.The center support frame assembly shown in FIG. 17 incorporates elevencenter subgrid units 18. Alternate configurations having more or lesscenter subgrid units may be utilized. The center subgrid units 18 aresecured to each other via clips 42 and clip apertures 40 along sidemembers of the center subgrid units 18. FIG. 17A shows attachment ofindividual center subgrid units such that the center support framesubassembly is created. As shown, the center support frame subassemblyis covered in screen elements 16. Alternatively, the center supportframe subassembly may be constructed from center subgrids prior toattachment of screen elements or partially from pre-covered subgridunits and partially from uncovered subgrid units.

FIG. 18 shows an exploded view of a screen assembly having three centersupport frame subassemblies and two end support frame subassemblies. Thesupport frame assemblies are secured to each other via the clips 42 andclip apertures 40 on the subgrid end members. Each center subgrid unitis attached to two other subgrid units via end members. End members 36of end subgrid units having no clips 42 or clip apertures 40 form theend edges of the screen assembly. The screen assembly may be made withmore or less center support frames subassemblies or larger or smallerframe subassemblies. Binder bars may be added to side edges of thescreen assembly. As shown, the screen assembly has screen elementsinstalled upon the subgrid units prior to assembly. Alternatively,screen elements 16 may be installed after all or a portion of assembly.

FIG. 19 illustrates an alternative embodiment of the present disclosurewhere screen assembly 54 is substantially flat. Screen assembly 54 maybe flexible such that it can be deformed into a concave or convex shapeor may be substantially rigid. Screen assembly 54 may be used with aflat screening surface. See FIG. 39. As shown, screen assembly 54 hasbinder bars 12 attached to side portions of the screen assembly 54.Screen assembly 54 may be configured with the various embodiments of thegrid structures and screen elements described herein.

FIG. 20 illustrates an alternative embodiment of the present disclosurewherein screen assembly 56 is convex. Screen assembly 56 may be flexiblesuch that it can be deformed into a more convex shape or may besubstantially rigid. As shown, screen assembly 56 has binder bars 12attached to side portions of the screen assembly. Screen assembly 56 maybe configured with the various embodiments of the grid structures andscreen elements described herein.

In alternative embodiments of the present disclosure, screen assembly410 is provided having screen elements 416, center subgrid units 418,and end subgrid units 414. See, e.g., FIG. 47. Screen element 416 may bethermoplastic injection molded and may include all of the features ofscreen element 16 provided above. Screen element 416 may be incorporatedinto any of the screen assemblies disclosed herein (e.g., 10 and 52-54)and is interchangeable with screen element 16. Screen element 416 mayinclude location apertures 424, which may be located at a center ofscreen element 416 and at 10 each of the four corners of screen element416. See, e.g., FIGS. 48 and 48A. More or less location apertures 424may be provided on screen element 416 and multiple configurations may beprovided. The location apertures 424 may be substantially the same asattachment apertures 24 and may be utilized to locate the screen element416 on a subgrid. Alternatively, screen element 416 may be locatedwithout location apertures 424. Screen element 416 may include aplurality of tapered counter bores 470, which may facilitate extractionof screen element 416 from a mold, which mold may have injector pinsconfigured to push the screen element out of the mold. See, e.g., FIGS.48 and 48A.

On a bottom side of screen element 416, a first adhesion arrangement maybe incorporated, which may be a plurality of extensions, cavities or acombination of extensions and cavities. The first adhesion arrangementof screen element 416 may be configured to mate with a complementarysecond adhesion arrangement on a top surface of a subgrid unit. Forexample, in FIGS. 48B and 48C a plurality of cavity pockets 472 areprovided. The plurality of cavity pockets 472 may be arranged along endportions 20 and side portions 22 between the location apertures 424.Additional cavity pockets 272 may be arranged along all or a portion offirst support screen element member 28 and along all or a portion ofsecond screen element support member 30. Although shown as elongatedcavities, cavity pockets 472 may have a variety of configurations,sizes, and depths. Moreover, the first adhesion arrangement on screenelement 416 may be extensions rather than cavities. The first adhesionarrangement of screen element 416 may be configured to mate with acomplimentary second adhesion arrangement on a subgrid unit such that aportion of screen element 416 overlaps at least a portion the subgridunit regardless of whether the screen element 416 or the subgrid unithas extensions or cavities.

End subgrid unit 414 and center subgrid unit 418 may be incorporatedinto screen assembly 410. See, e.g., FIGS. 49, 49A, 50, and 50A. Endsubgrid unit 414 and center subgrid unit 418 may be thermoplasticinjection molded and may include all of the features of end subgrid unit14 and center subgrid unit 18 discussed above. End subgrid unit 414 andcenter subgrid unit 418 may be interchangeably used wherever end subgridunit 14 and center subgrid unit 18 are indicated. End subgrid unit 414and center subgrid unit 418 may have a plurality elongated locationmembers 444, which may be substantially the same as attachment members44. The arrangement of location members 444 may correspond to thelocation apertures 424 of screen elements 416 such that screen elements416 may be located onto end subgrid unit 414 and center subgrid unit 418for attachment.

End subgrid unit 414 and center subgrid unit 418 may include a secondadhesion arrangement on a top surface of each of end subgrid unit 414and center subgrid unit 418, which second adhesion arrangement may becomplimentary to the first adhesion arrangement of screen element 416such that the screen element may be mated to a subgrid unit via themating of the first and second adhesion arrangements. In one embodimentof the present invention, the second adhesion arrangement may be aplurality of fusion bars 476 arranged along a top surface of subgridside members 38 and subgrid end members 36. End subgrid unit 414 andcenter subgrid unit 418 may also include a plurality of fusion bars 478,which may be shortened fusion bars having heights less than heights offusion bars 476, arranged along a top surface of first subgrid supportmember 46 and second subgrid support member 48. See, e.g., FIGS. 49 to50A. Although shown as elongated extensions, fusion bars 476 (and 478)may be various shapes and sizes and may be arranged in a variety ofconfigurations. Alternatively, the second adhesion arrangement may becavities, pockets, or similar and may be configured to receiveextensions from a screen element. The second adhesion arrangement couldinclude both extensions and cavities.

Each of the plurality of cavity pockets 472 is configured to receivefusion bars 476 and shorted fusion bars 478 arranged on subgrids (414,418, 458, and 460). See, e.g., FIGS. 45A to 45E and 46. As shown inFIGS. 45B to 45E, fusion bars 476 fit within the plurality of cavitypockets 472 when screen element 416 is placed upon a subgrid. Cavitypockets 472 may have a width C that is slightly larger than width D offusion bar 476. Cavity pocket 472 may have a depth A that is slightlysmaller than a height B of fusion bar 476. See, e.g., FIG. 47. Height Bof fusion bar 476 may be approximately 0.056 inches. Prior to melting offusion bars 476, screen element 416 may rest upon fusion bars 476without contacting the rest of a subgrid. Screen element 416 and thesubgrids may be bonded together via laser welding. Bonding may beaccomplished through chemical bonding between the cavity pockets 472 andthe fusion bars (476 or 478) or melting portions of the materials ofeach component such that the components harden together. In oneembodiment, when screen element 416 is located on a subgrid, fusion bar476 (or shortened fusion bar 478) may be melted, allowing for a meltedportion of the fusion bar 476 to fill all or a portion of width C of thecavity pocket 472. In certain embodiments approximately 0.006 inches offusion bar 476 may be melted and allowed to fill all or a portion of thewidth of cavity pocket 472. Melting of fusion bar 476 may be performedvia laser welding, which may secure screen element 416 to a subgrid. Alaser 500 may be configured and controlled to reach a specific depth offusion bar 476.

Fusion bars 476 (or shortened fusion bars 478) may include carbon,graphite or other materials configured to respond to a specific laserwavelength. The fusion bars may be further configured to correspond to alaser to be used for laser welding. Fusion bars may have specificlengths to correspond to a laser 500. Although shown as elongatedprotrusions, other shapes and/or designs may be incorporated for fusionbars subject to the requirements of a chosen laser. In embodimentshaving fusion bars on subgrids, screen elements 416 typically do notinclude carbon or graphite. Screen element 416 and the fusion bars maybe made of different materials such that a selected laser 500 may travelthrough screen element 416 without melting screen element 416 andcontact the fusion bars. See, e.g., FIGS. 45B and C. Screen element 416may be made of a TPU or similar material having performance propertiesdesired for a screening application. Screen element 416 may besubstantially clear. Subgrids (414 and 418) may be made from nylon orsimilar materials. The fusion bars may have a higher melting point thanthe material of screen element 416 such that, when the fusion bars aremelted, a portion of the screen element 416 also melts, which may beaccomplished by heat transfer from the melted portion of fusion bar 476that contacts screen element 416 in the cavity pocket 472. In this way,screen element 416 is welded to a subgrid. See, e.g., FIGS. 51, 51A, 52,and 52A.

Laser welding is typically performed by focusing a laser beam toward aseam or area to transform material from a solid to a liquid, and afterremoval of the laser beam, the material return to a solid. Laser weldingis a type of fusion welding and can be performed through conduction orpenetration. Conduction welding relies upon conductivity of the materialbeing welded to generate heat and melt the material. Laser welding ofscreen element 416 to a subgrid having fusion bars provides for laserwelding of two different materials together. Typically, this cannot beaccomplished with laser welding; however, applying the laser 500 throughthe screen element 416 to the fusion bars, which have conductiveproperties to generate heat upon the application of the selected laser500, cause the fusion bars (476 or 478) to melt. Similarly, the heatproduced by the conduction and/or from the melted fusion bar materialcauses a portion of the screen element to melt. The two liquid materialscombine and create a strong solid attachment between the subgrid and thescreen element when the laser is removed and the combined materialsreturn to a solid. By forming laser welded bonds between the screenelement and the subgrids, the attachment between the components is verystrong, which is essential for components of screen assemblies used invibratory screening machines. The screen assemblies can be subjected tovibratory forces in excess of 8 Gs, abrasive materials and chemicals,and very high load requirements. Therefore, screen assemblies must bevery strong and durable. Embodiments of the present invention providescreen assemblies made from multiple parts secured together. Creatingscreen assemblies from smaller subparts allows for micro injectionmolding of screen elements with very small openings, e.g. having athickness of approximately 43 microns to approximately 100 microns. Thestrength of the laser welding adds overall strength to the screenassemblies, allowing for the benefits of micro injection molding thescreen elements while maintaining durable screen assemblies. Laserwelding also provides a more efficient attachment procedure than otherattachment procedures such as heat staking. In certain embodiments,laser welding may be accomplished in approximately 8 to 10 seconds whereheat staking involving other embodiments may require approximately 1.5minutes.

End subgrid unit 414 (or 14) and center subgrid unit 418 (or 18) mayinclude secondary support framework 488 spanning across grid openings50. Secondary support framework 488 may span all or only a portion of agrid opening 50. Secondary support framework 488 increases the strengthand durability of end subgrid unit 414 (or 14) and center subgrid unit418 (or 18). Secondary support framework 488 increases the overallstrength of screen assembly 410 allowing it to withstand vibratoryforces in excess of 8 Gs.

FIGS. 21 and 21A show an alternative embodiment of the presentdisclosure incorporating pyramidal shaped subgrid units. A screenassembly is shown with binder bars 12 attached. The screen assemblyincorporates center and end subgrid units 14 and 18 (or 414 and 418) andcenter and end pyramidal shaped subgrid units 58 and 60 (or 458 and460). By incorporating the pyramidal shaped subgrid units 58 and 60 intothe screen assembly, an increased screening surface may be achieved.Additionally, material being screened may be controlled and directed.The screen assembly may be concave, convex, or flat. The screen assemblymay be flexible and may be deformed into a concave or convex shape uponthe application of a compression force. The screen assembly may includeguide notches capable of mating with guide mating surfaces on avibratory screening machine. Different configurations of subgrid unitsand pyramid subgrid units may be employed which may increase or decreasean amount of screening surface area and flow characteristics of thematerial being processed. Unlike mesh screens or similar technology,which may incorporate corrugations or other manipulations to increasesurface area, the screen assembly shown is supported by the gridframework, which may be substantially rigid and capable of withstandingsubstantial loads without damage or destruction. Under heavy materialflows, traditional screen assemblies with corrugated screening surfacesare frequently flattened or damaged by the weight of the material,thereby impacting the performance and reducing the screening surfacearea of such screen assemblies. The screen assemblies disclosed hereinare difficult to damage because of the strength of the grid framework,and the benefits of increased surface area provided by incorporatingpyramidal shaped subgrids may be maintained under substantial loads.

A pyramidal shaped end subgrid 58 is illustrated in FIG. 22 and FIG.22A. Pyramidal shaped end subgrid 58 includes a first and a second gridframework forming first and second sloped surface grid openings 74.Pyramidal shaped end subgrid 58 includes a ridge portion 66, subgridside members/base members 64, and first and second angular surfaces 70and 72, respectively, that peak at ridge portion 66 and extenddownwardly to side member 64. Pyramidal shaped subgrids 58 and 60 havetriangular end members 62 and triangular middle support members 76.Angles shown for first and second angular surface 70 and 72 areexemplary only. Different angles may be employed to increase or decreasesurface area of screening surface. Pyramidal shaped end subgrid 58 hasfasteners along side members 64 and at least one triangle end member 62.The fasteners may be clips 42 and clip apertures 40 such that multiplesubgrid units 58 may be secured together. Alternatively, the clips 42and clip apertures 40 may be used to secure pyramidal shaped end subgrid58 to end subgrid 14, center subgrid 18, or pyramidal shaped centersubgrid 60. Elongated attachment members 44 may be configured on firstand second sloped surfaces 70 and 72 such that they mate with the screenelement attachment apertures 24. Screen element 16 may be secured topyramidal shaped end subgrid 58 via mating elongated attachment members44 with the screen element attachment apertures 24. A portion of theelongated attachment member 44 may extend slightly above the screenelement screening surface when the screen element 16 is attached topyramidal shaped end subgrid 58. The screen element attachment apertures24 may include a tapered bore such that a portion of the elongatedattachment members 44 extending above the screen element screeningsurface may be melted and fill the tapered bore. Alternatively, thescreen element attachment apertures 24 may be without a tapered bore andthe portion of the elongated attachment members extending above thescreening surface of the screening element 16 may be melted to form abead on the screening surface. Once attached, screen element 16 may spanfirst 74 and second sloped grid openings. Materials passing through thescreening openings 86 will pass through the first 74 and second gridopenings.

A pyramidal shaped center subgrid 60 is illustrated in FIG. 23 and FIG.23A. Pyramidal shaped center subgrid 60 includes a first and a secondgrid framework forming a first and second sloped surface grid opening,74. Pyramidal shaped center subgrid 60 includes a ridge portion 66, asubgrid side members/base members 64, and first and second angularsurfaces 70 and 72 that peak at the ridge portion 66 and extenddownwardly to the side member 64. Pyramidal shaped center subgrid 60 hastriangular end members 62 and triangular middle members 76. Angles shownfor first and second angular surface 70 and 72 are exemplary only.Different angles may be employed to increase or decrease surface area ofscreening surface. The pyramidal shaped center subgrid 60 has fastenersalong side members 64 and both triangle end members 62. The fasters maybe clips 42 and clip apertures 40 such that multiple pyramidal shapedcenter subgrids 60 may be secured together. Alternatively, the clips 42and clip apertures 40 may be used to secure pyramidal shaped centersubgrid 60 to end subgrid 14, center subgrid 18, or pyramidal shaped endsubgrid 58. Elongated attachment members 44 may be configured on firstand second sloped surfaces 70 and 72 such that they mate with the screenelement attachment apertures 24. Screen element 16 may be secured topyramidal shaped center subgrid 60 via mating elongated attachmentmembers 44 with the screen element attachment apertures 24. A portion ofthe elongated attachment member 44 may extend slightly above the screenelement screening surface when the screen element 16 is attached topyramidal shaped center subgrid 60. The screen element attachmentapertures 24 may include a tapered bore such that the portion of theelongated attachment members 44 extending above the screen elementscreening surface may be melted and fill the tapered bore.Alternatively, the screen element attachment apertures 24 may be withouta tapered bore and the portion of the elongated attachment membersextending above the screening surface of the screening element 16 may bemelted to form a bead on the screening surface. Once attached, screenelement 16 will span sloped grid opening 74. Materials passing throughthe screening openings 86 will pass through the grid opening 74. Whilepyramid and flat shaped grid structures are shown, it will beappreciated that various shaped subgrids and corresponding screenelements may be fabricated in accordance with the present disclosure.

FIG. 24 shows a subassembly of a row of pyramidal shaped subgrid units.FIG. 24A is an exploded view of the subassembly in FIG. 24 showing theindividual pyramidal shaped subgrids and direction of attachment. Thesubassembly includes two pyramidal shaped end subgrids 58 and threepyramidal shaped center subgrids 60. The pyramidal shaped end subgrids58 form ends of the subassembly while pyramidal shaped center subgrids60 are used to join the two end subgrids 58 via connections between theclips 42 and clip apertures 40. The pyramidal subgrids shown in FIG. 24are shown with attached screen elements 16. Alternatively, thesubassembly may be constructed from subgrids prior to attachment ofscreen elements or partially from pre-covered pyramidal shaped subgridunits and partially from uncovered pyramidal shaped subgrid units.

FIGS. 24B and 24C illustrate attachment of screen elements 16 topyramidal shaped end subgrid 58, according to an exemplary embodiment ofthe present invention. Screen elements 16 may be aligned with pyramidalshaped end subgrid 58 via elongated attachment members 44 and screenelement attachment apertures 24 such that the elongated attachmentmembers 44 pass through the screen element attachment apertures 24 mayextend slightly beyond the screen element screening surface. The portionof elongated attachment members 44 extending beyond screen elementscreening surface may be melted to fill tapered bores of the screenelement attachment apertures 24 or, alternatively, to form beads uponthe screen element screening surface, securing the screen element 16 topyramidal shaped subgrid 58. Attachment via elongated attachment members44 and screen element attachment apertures 24 is only one embodiment ofthe present invention. Alternatively, screen element 16 may be securedto pyramidal shaped end subgrid 58 via adhesive, fasteners and fastenerapertures, etc. Although shown having four screen elements for eachpyramidal shaped end subgrid 58, the present invention includesalternate configurations of two screen elements per pyramidal shaped endsubgrid 58, multiple screen elements per pyramidal shaped end subgrid58, or having a single screen element cover a sloped surface of multiplepyramidal shaped subgrid units. Pyramidal shaped end subgrid 58 may besubstantially rigid and may be a single thermoplastic injection moldedpiece.

FIGS. 24D and 24E illustrate attachment of screen elements 16 topyramidal shaped center subgrid 60, according to an exemplary embodimentof the present invention. Screen elements 16 may be aligned withpyramidal shaped center subgrid 60 via elongated attachment members 44and screen element attachment apertures 24 such that the elongatedattachment members 44 may pass through the screen element attachmentapertures 24 and may extend slightly beyond the screen element screeningsurface. The portion of the elongated attachment members 44 extendingbeyond screen element screening surface may be melted to fill taperedbores of the screen element attachment apertures 24 or, alternatively,to form beads upon the screen element screening surface, securing thescreen element 16 to pyramidal shaped subgrid unit 60. Attachment viaelongated attachment members 44 and screen element attachment apertures24 is only one embodiment of the present invention. Alternatively,screen element 16 may be secured to pyramidal shaped center subgrid 60via adhesive, fasteners and fastener apertures, etc. Although shownhaving four screen elements for each pyramidal shaped center subgrid 60,the present invention includes alternate configurations of two screenelements per pyramidal shaped center subgrid 60, multiple screenelements per pyramidal shaped center subgrid 60, or having a singlescreen element cover a sloped surface of multiple pyramidal shapedsubgrids. Pyramidal shaped center subgrid 60 may be substantially rigidand may be a single thermoplastic injection molded piece. While pyramidand flat shaped grid structures are shown, it will be appreciated thatvarious shaped subgrids and corresponding screen elements may befabricated in accordance with the present disclosure.

FIGS. 53 to 56A show end and center pyramidal shaped subgrids 458 and460, respectively, according to exemplary embodiments of the presentdisclosure. End and center pyramidal shaped subgrids 458 and 460 may bethermoplastic injection molded and may have all of the features of endand center pyramidal shaped subgrids 58 and 60 discussed herein above.As with end subgrid unit 414 and center subgrid unit 418, end and centerpyramidal shaped subgrids 458 and 460 may have location members 444corresponding to the location apertures 424 of screen element 416 suchthat screen elements 416 may be located onto end and center pyramidalshaped subgrids 458 and 460 for attachment. End and center pyramidalshaped subgrids 458 and 460 may have second adhesion arrangements suchas a plurality of fusion bars 476 and shorted fusion bars 478. Thesecond adhesion arrangements may be configured to mate withcomplimentary first adhesion arrangements on screen elements 416 such asa plurality of pocket cavities. Screen elements 416 may be laser weldedto the pyramidal subgrids. End and center pyramidal shaped subgrids 458and 460 may include secondary support framework 488 spanning across gridopenings 74. Secondary support framework 488 may span all or only aportion of a grid opening 74. Secondary support framework 488 increasesthe strength and durability of end and center pyramidal shaped subgrids458 and 460. End and center pyramidal shaped subgrids 458 and 460 mayinclude a flattened ridge portion 465 and may have fixture locators 490in ridge 66. See, e.g., FIG. 53. Flattened ridge portion 465 may allowfor easier molding than rounded or pointed embodiments and may allow foreasier release and/or extraction of the subgrids from molds. Embodimentsmay include one or more fixture locators 490 which may be utilized inalignment and/or assembly during laser welding. Fixtures may engagesubgrids at fixture locators 490 allowing for alignment of laserwelding. Flattened ridge portion 465 may provide easier engagement ofthe fixture locators 490.

FIG. 25 is a top view of a screen assembly 80 having pyramidal shapedsubgrids, which may be any of subgrids 14, 18, 414, and 418. As shown,the screen assembly 80 is formed from screen subassemblies attached toeach other alternating from flat subassemblies to pyramidal shapedsubassemblies. Alternatively, pyramidal shaped subassemblies may beattached to each other or less or more pyramidal shaped subassembliesmay be used. FIG. 25A is a cross-section of Section C-C of the screenassembly shown in FIG. 25. As shown, the screen assembly has five rowsof pyramidal shaped subgrid units and six rows of flat subgrids, withthe rows of flat subgrid units in between each row of the pyramidalshaped subgrids. Binder bars 12 are attached to the screen assembly. Anycombination of flat subgrid rows and pyramidal shaped subgrid rows maybe utilized. FIG. 25B is a larger view of the cross-section shown inFIG. 25A. In FIG. 25B, attachment of each subgrid to another subgridand/or binder bar 12 is visible via clips and clip apertures.

FIG. 26 is an exploded isometric view of a screen assembly havingpyramidal shaped subgrid units. This figure shows eleven subassembliesbeing secured to each other via clips and clip apertures along subgridside members of subgrid units in each subassembly. Each flat subassemblyhas two end subgrids (14 or 414) and three center subgrids (18 or 418).Each pyramidal shaped subassembly has two pyramidal shaped end subgrids(58 or 458) and three pyramidal shaped center subgrids (60 or 460).Binder bars 12 are fastened at each end of the assembly. Different sizescreen assemblies may be created using different numbers ofsubassemblies or different numbers of center subgrid units. Screeningsurface area may be increased by incorporating more pyramidal shapedsubassemblies or decreased by incorporating more flat assemblies. Anassembled screen assembly has a continuous screen assembly screeningsurface made up of multiple screen element screening surfaces.

FIG. 27 shows installation of screen assemblies 80 upon a vibratoryscreening machine having two screening surfaces. FIG. 30 is a front viewof the vibratory machine shown in FIG. 27. The vibratory screeningmachine may have compression assemblies on side members of the vibratoryscreening machine. The screen assemblies may be placed into thevibratory screening machine as shown. A compression force may be appliedto a side member of the screen assembly such that the screen assemblydeflects downward into a concave shape. A bottom side of the screenassembly may mate with a screen assembly mating surface of the vibratoryscreening machine as shown in U.S. Pat. No. 7,578,394 and U.S. patentapplication Ser. No. 12/460,200. The vibratory screening machine mayinclude a center wall member configured to receive a side member of thescreen assembly opposite of the side member of the screen assemblyreceiving compression. The center wall member may be angled such that acompression force against the screen assembly deflects the screenassembly downward. The screen assembly may be installed in the vibratoryscreening machine such that it is configured to receive material forscreening. The screen assembly may include guide notches configured tomate with guides of the vibratory screening machine such that the screenassembly may be guided into place during installation.

FIG. 28 shows an isometric view of a screen assembly having pyramidalshaped subgrids where screen elements have not been attached. The screenassembly shown in FIG. 28 is slightly concave, however, the screenassembly may be more concave, convex or flat. The screen assembly may bemade from multiple subassemblies, which may be any combination of flatsubassemblies and pyramidal shaped subassemblies. As shown, elevensubassemblies are included, however, more or less subassemblies may beincluded. The screen assembly is shown without screen elements 16 (or416). The subgrids may be assembled together before or after attachmentof screen elements to subgrids or any combination of subgrids havingattached screen elements and subgrids without screen elements may befastened together. FIG. 29 shows the screen assembly of FIG. 28partially covered in screen elements. Pyramidal shaped subassembliesinclude pyramidal shaped end subgrids 58 and pyramidal shaped centersubgrids 60. Flat subassemblies include flat end subgrids 14 and flatcenter subgrids 18. The subgrid units may be secured to each other viaclips and clip apertures.

FIG. 31 shows installation of screen assembly 81 in a vibratoryscreening machine having a single screening surface, according to anexemplary embodiment of the present invention. Screen assembly 81 issimilar in configuration to screen assembly 80 but includes additionalpyramid and flat assemblies. The vibratory screening machine may have acompression assembly on a side member of the vibratory screeningmachine. Screen assembly 81 may be placed into the vibratory screeningmachine as shown. A compression force may be applied to a side member ofscreen assembly 81 such that screen assembly 81 deflects downward into aconcave shape. A bottom side of the screen assembly may mate with ascreen assembly mating surface of the vibratory screening machine asshown in U.S. Pat. No. 7,578,394 and U.S. patent application Ser. No.12/460,200. The vibratory screening machine may include a side memberwall opposite of the compression assembly configured to receive a sidemember of the screen assembly. The side member wall may be angled suchthat a compression force against the screen assembly deflects the screenassembly downward. The screen assembly may be installed in the vibratoryscreening machine such that it is configured to receive material forscreening. The screen assembly may include guide notches configured tomate with guides of the vibratory screening machine such that the screenassembly may be guided into place during installation.

FIG. 32 is a front view of screen assemblies 82 installed upon avibratory screening machine having two screening surfaces, according toan exemplary embodiment of the present invention. Screen assembly 82 isan alternate embodiment where the screen assembly has been preformed tofit into the vibratory screening machine without applying a load to thescreen assembly, i.e., screen assembly 82 includes a bottom portion 82Athat is formed such that it mates with a bed 83 of the vibratoryscreening machine. The bottom portion 82A may be formed integrally withscreen assembly 82 or it may be a separate piece. Screen assembly 82includes similar features as screen assembly 80, including subgrids andscreen elements but also includes bottom portion 82A that allows it tofit onto bed 83 without being compressed into a concave shape. Ascreening surface of screen assembly 82 may be substantially flat,concave or convex. Screen assembly 82 may be held into place by applyinga compression force to a side member of screen assembly 82 or may simplybe held in place. A bottom portion of screen assembly 82 may bepreformed to mate with any type of mating surface of a vibratoryscreening machine.

FIG. 33 is a front view of screen assembly 85 installed upon a vibratoryscreening machine having a single screening surface, according to anexemplary embodiment of the present invention. Screen assembly 85 is analternate embodiment where the screen assembly has been preformed to fitinto the vibratory screening machine without applying a load to thescreen assembly i.e., screen assembly 85 includes a bottom portion 85Athat is formed such that it mates with a bed 87 of the vibratoryscreening machine. The bottom portion 85A may be formed integrally withscreen assembly 85 or it may be a separate piece. Screen assembly 85includes similar features as screen assembly 80, including subgrids andscreen elements but also includes bottom portion 85A that allows it tofit onto bed 87 without being compressed into a concave shape. Ascreening surface of screen assembly 85 may be substantially flat,concave or convex. Screen assembly 85 may be held into place by applyinga compression force to a side member of screen assembly 85 or may simplybe held in place. A bottom portion of screen assembly 85 may bepreformed to mate with any type of mating surface of a vibratoryscreening machine.

FIG. 34 is an isometric view of the end subgrid shown in FIG. 3 having asingle screen element partially attached thereto. FIG. 35 is an enlargedview of break out section E of the end subgrid shown in FIG. 34. InFIGS. 34 and 35, screen element 16 is partially attached to end subgrid38. Screen element 16 is aligned with subgrid 38 via elongatedattachment members 44 and screen element attachment apertures 24 suchthat the elongated attachment members 44 pass through the screen elementattachment apertures 24 and extend slightly beyond the screen elementscreening surface. As shown along the end edge portion of screen element16, the portions of the elongated attachment members 44 extending beyondscreen element screening surface are melted to form beads upon thescreen element screening surface, securing the screen element 16 to endsubgrid unit 38.

FIG. 36 shows a slightly concave screen assembly 91 having pyramidalshaped subgrids incorporated into a portion of screen assembly 91according to an exemplary embodiment of the present invention. Ascreening surface of the screen assembly may be substantially flat,concave or convex. The screen assembly 91 may be configured to deflectto a predetermined shape under a compression force. The screen assembly91, as shown in FIG. 36, incorporates pyramidal shaped subgrids in theportion of the screen assembly installed nearest the inflow of materialon the vibratory screening machine. The portion incorporating thepyramidal shaped subgrids allows for increased screening surface areaand directed material flow. A portion of the screen assembly installednearest a discharge end of the vibratory screening machine incorporatesflat subgrids. On the flat portion, an area may be provided such thatmaterial may be allowed to dry and/or cake on the screen assembly.Various combinations of flat and pyramidal subgrids may be included inthe screen assembly depending on the configuration desired and/or theparticular screening application. Further, vibratory screening machinesthat use multiple screen assemblies may have individual screenassemblies with varying configurations designed for use together onspecific applications. For example, screen assembly 91 may be used withother screen assemblies such that it is positioned near the dischargeend of a vibratory screening machine such that it provides for cakingand/or drying of a material.

FIG. 37 is a flow chart showing steps to fabricate a screen assembly,according to an exemplary embodiment of the present invention. As shownin FIG. 37, a screen fabricator may receive screen assembly performancespecifications for the screen assembly. The specifications may includeat least one of a material requirement, open screening area, capacityand a cut point for a screen assembly. The fabricator may then determinea screening opening requirement (shape and size) for a screen element asdescribed herein. The fabricator may then determine a screenconfiguration (e.g., size of assembly, shape and configuration ofscreening surface, etc.). For example, the fabricator may have thescreen elements arranged in at least one of a flat configuration and anonflat configuration. A flat configuration may be constructed fromcenter subgrids (18 or 418) and end subgrids (14 or 414). A nonflatconfiguration may include at least a portion of pyramidal shaped centersubgrids (60 or 460) and/or pyramidal shaped end subgrids (58 or 458).Screen elements may be injection molded. Subgrid units may also beinjection molded but are not required to be injection molded. Screenelements and subgrids may include a nanomaterial, as described herein,dispersed within. After both screen elements and subgrid units have beencreated, screen elements may be attached to subgrid units. The screenelements and subgrids may be attached together using connectionmaterials having a nanomaterial dispersed within. Screen elements may beattached to subgrids using laser welding. Multiple subgrid units may beattached together forming support frames. Center support frames areformed from center subgrids and end support frames are formed from endsubgrids. Pyramidal shaped support frames may be created from pyramidalshaped subgrid units. Support frames may be attached such that centersupport frames are in a center portion of the screen assembly and endsupport frames are on an end portion of the screen assembly. Binder barsmay be attached to the screen assembly. Different screening surfaceareas may be accomplished by altering the number of pyramidal shapedsubgrids incorporated into the screen assembly. Alternatively, screenelements may be attached to subgrid units after attachment of multiplesubgrids together or after attachment of multiple support framestogether. Instead of multiple independent subgrids that are attachedtogether to form a single unit, one subgrid structure may be fabricatedthat is the desired size of the screen assembly. Individual screenelements may then be attached to the one subgrid structure.

FIG. 38 is a flow chart showing steps to fabricate a screen assembly,according to an exemplary embodiment of the present invention. Athermoplastic screen element may be injection molded. Subgrids may befabricated such that they are configured to receive the screen elements.Screen elements may be attached to subgrids and multiple subgridassemblies may be attached, forming a screening surface. Alternatively,the subgrids may be attached to each other prior to attachment of screenelements.

In another exemplary embodiment, a method for screening a material isprovided, including attaching a screen assembly to a vibratory screeningmachine and forming a top screening surface of the screen assembly intoa concave shape, wherein the screen assembly includes a screen elementhaving a series of screening openings forming a screen element screeningsurface and a subgrid including multiple elongated structural membersforming a grid framework having grid openings. The screen elements spangrid openings and are secured to a top surface of the subgrid. Multiplesubgrids are secured together to form the screen assembly and the screenassembly has a continuous screen assembly screening surface comprised ofmultiple screen element screening surfaces. The screen element is asingle thermoplastic injection molded piece.

FIG. 39 is an isometric view of a vibratory screening machine having asingle screen assembly 89 with a flat screening surface installedthereon with a portion of the vibratory machine cut away showing thescreen assembly. Screen assembly 89 is a single unit that includes asubgrid structure and screen elements as described herein. The subgridstructure may be one single unit or may be multiple subgrids attachedtogether. While screen assembly 89 is shown as a generally flat typeassembly, it may be convex or concave and may be configured to bedeformed into a concave shape from a compression assembly or the like.It may also be configured to be tensioned from above or below or may beconfigured in another manner for attachment to different types ofvibratory screening machines. While the embodiment of the screenassembly shown covers the entire screening bed of the vibratoryscreening machine, screen assembly 89 may also be configured in anyshape or size desired and may cover only a portion of the screening bed.

FIG. 40 is an isometric view of a screen element 99 according to anexemplary embodiment of the present invention. Screen element 99 issubstantially triangular in shape. Screen element 99 is a singlethermoplastic injection molded piece and has similar features (includingscreening opening sizes) as screen elements 16 and 416 as describedherein. Alternatively, the screen element may be rectangular, circular,triangular, square, etc. Any shape may be used for the screen elementand any shape may be used for the subgrid as long as the subgrid hasgrid openings that correspond to the shapes of the screen elements.

FIGS. 40A and 40B show screen element structure 101, which may be asubgrid type structure, with screen elements 99 attached thereto forminga pyramid shape. In an alternative embodiment the complete pyramidstructure of screen element structure 101 may be thermoplastic injectionmolded as a single screen element having a pyramid shape. In theconfiguration shown, the screen element structure has four triangularscreen element screening surfaces. The bases of two of the triangularscreening surfaces begin at the two side members of the screen elementand the bases of the other two triangular screening surfaces begin atthe two end members of the screen element. The screening surfaces allslope upward to a center point above the screen element end members andside members. The angle of the sloped screening surfaces may be varied.Screen element structure 101 (or alternatively single screen elementpyramids) may be attached to a subgrid structure as described herein.

FIGS. 40C and 40D show a screen element structures 105 with screenelements 99 attached and having a pyramidal shape dropping below sidemembers and edge members of the screen element structure 105.Alternatively, the entire pyramid may be thermoplastic injection moldedas a single pyramid shaped screen element. In the configuration shown,individual screen elements 99 form four triangular screening surfaces.The bases of two of the triangular screening surfaces begin at the twoside members of the screen element and the bases of the other twotriangular screening surfaces begin at the two end members of the screenelement. The screening surfaces all slope downward to a center pointbelow the screen element end members and side members. The angle of thesloped screening surfaces may be varied. Screen element structure 105(or alternatively single screen element pyramids) may be attached to asubgrid structure as described herein.

FIGS. 40E and 40F show a screen element structure 107 having multiplepyramidal shapes dropping below and rising above the side members andedge members of screen element structure 107. Each pyramid includes fourindividual screen elements 99 but may also be formed as single screenelement pyramid. In the configuration shown, each screen element hassixteen triangular screening surfaces forming four separate pyramidalscreening surfaces. The pyramidal screening surfaces may slope above orbelow the screen element end members and side members. Screen elementstructure 107 (or alternatively single screen element pyramids) may beattached to a subgrid structure as described herein. FIGS. 40 through40F are exemplary only as to the variations that may be used for thescreen elements and screen element support structures.

FIGS. 41 to 43 show cross-sectional profile views of exemplaryembodiments of thermoplastic injection molded screen element surfacestructures that may be incorporated into the various embodiments of thepresent invention discussed herein. The screen element is not limited tothe shapes and configurations identified herein. Because the screenelement is thermoplastic injection molded, multiple variations may beeasily fabricated and incorporated into the various exemplaryembodiments discussed herein.

FIG. 44 shows a prescreen structure 200 for use with vibratory screeningmachines. Prescreen structure 200 includes a support frame 300 that ispartially covered with individual prescreen assemblies 210. Prescreenassemblies 210 are shown having multiple prescreen elements 216 mountedon prescreen subgrids 218. Although, prescreen assemblies 210 are shownincluding six prescreen subgrids 218 secured together, various numbersand types of subgrids may be secured together to form various shapes andsizes of prescreen assemblies 210. The prescreen assemblies 210 arefastened to support frame 300 and form a continuous prescreening surface213. Prescreen structure 200 may be mounted over a primary screeningsurface. Prescreen assemblies 210, prescreen elements 216 and theprescreen subgrids 218 may include any of the features of the variousembodiments of screen assemblies, screen elements and subgrid structuresdescribed herein and may configured to be mounted on prescreen supportframe 300, which may have various forms and configurations suitable forprescreening applications. Prescreen structure 200, prescreen assemblies210, prescreen elements 216 and the prescreen subgrids 218 may beconfigured to be incorporated into the prescreening technologies (e.g.,compatible with the mounting structures and screen configurations)described in U.S. patent application Ser. No. 12/051,658.

FIG. 44A shows an enlarged view of prescreen assembly 210.

The embodiments of the present invention described herein, includingscreening members and screening assemblies, may be configured for usewith various different vibratory screening machines and parts thereof,including machines designed for wet and dry applications, machineshaving multi-tiered decks and/or multiple screening baskets, andmachines having various screen attachment arrangements such astensioning mechanisms (under and overmount), compression mechanisms,clamping mechanisms, magnetic mechanisms, etc. For example, the screenassemblies described in the present disclosure may be configured to bemounted on the vibratory screening machines described in U.S. Pat. Nos.7,578,394; 5,332,101; 6,669,027; 6,431,366; and 6,820,748. Indeed, thescreen assemblies described herein may include: side portions or binderbars including U-shaped members configured to receive overmount typetensioning members, e.g., as described in U.S. Pat. No. 5,332,101; sideportions or binder bars including finger receiving apertures configuredto receive undermount type tensioning, e.g., as described in U.S. Pat.No. 6,669,027; side members or binder bars for compression loading,e.g., as described in U.S. Pat. No. 7,578,394; or may be configured forattachment and loading on multi-tiered machines, e.g., such as themachines described in U.S. Pat. No. 6,431,366. The screen assembliesand/or screening elements may also be configured to include featuresdescribed in U.S. patent application Ser. Nos. 12/460,200, including theguide assembly technologies described therein and preformed paneltechnologies described therein. Still further, the screen assemblies andscreening elements may be configured to be incorporated into theprescreening technologies (e.g., compatible with the mounting structuresand screen configurations) described in U.S. patent application Ser. No.12/051,658. U.S. Pat. Nos. 7,578,394; 5,332,101; 4,882,054; 4,857,176;6,669,027; 7,228,971; 6,431,366; and 6,820,748 and U.S. patentapplication Ser. Nos. 12/460,200 and 12/051,658, which, along with theirrelated patent families and applications, and the patents and patentapplications referenced in these documents, are expressly incorporatedherein by reference hereto.

In the foregoing, example embodiments are described. It will, however,be evident that various modifications and changes may be made thereuntowithout departing from the broader spirit and scope hereof. Thespecification and drawings are accordingly to be regarded in anillustrative rather than in a restrictive sense.

What is claimed is:
 1. A method for fabricating a screen assembly forscreening materials, comprising: injection molding a screen element, thescreen element including a screen element screening surface havingscreening openings; fabricating a subgrid that supports the screenelement, the subgrid having a grid framework with grid openings, thescreen element spanning at least one grid opening wherein at least oneof the screen element and the subgrid is a single thermoplasticinjection molded piece; and securing the screen element to a top surfaceof the subgrid, the screen assembly having a continuous screen assemblyscreening surface comprised of multiple screen element screeningsurfaces.
 2. The method of claim 1, further comprising attaching a firstbinder bar to a first end of the screen assembly and attaching a secondbinder bar to a second end of the screen assembly, wherein the first andsecond binder bars bind the subgrids together.
 3. The method of claim 2,wherein the binder bar is configured to distribute a load across thefirst and second ends of the screen assembly.
 4. The method of claim 1,wherein the screen element includes screen surface elements forming thescreening openings, the screening openings being elongated slots havinga distance of approximately 43 microns to approximately 1000 micronsbetween inner surfaces of each screen surface element.
 5. The method ofclaim 1, wherein the screen element includes screen surface elementsforming the screening openings, the screening openings being elongatedslots having a distance of approximately 70 microns to approximately 180microns between inner surfaces of each screen surface element.
 6. Themethod of claim 1, wherein the screen element includes screen surfaceelements forming the screening openings, the screening opening beingelongated slots having a distance of approximately 43 microns toapproximately 106 microns between inner surfaces of each screen surfaceelement.
 7. The method of claim 1, wherein the screen element includesscreen surface elements forming the screening openings, the screeningopenings being elongated slots having a width and a length, the widthbeing about 0.044 mm to about 4 mm and the length being about 0.088 mmto about 60 mm.
 8. The method of claim 1, wherein the subgrid includesat least one base member having fasteners that mate with fasteners ofother base members of other subgrids and secure the subgrids together.9. The method of claim 8, wherein the fasteners are clips and clipapertures that snap into place and securely attach the subgridstogether.
 10. The method of claim 1, wherein the screen element includesa screen element attachment arrangement configured to mate with asubgrid attachment arrangement.
 11. The method of claim 1, furthercomprising attaching multiple subgrids together to form the screenassembly.